user42159: I've bought a BSFrance LoRA32u4 from DIYmall on eBay UK.
https://bsfrance.fr/lora-long-range/1311-BSFrance-LoRa32u4-1KM-Long-Range-Board-Based-Atmega32u4-433MHz-LoRA-RA02-Module.html
I've copied the "bsfrance" directory (from the ZIP) into Arduino/hardware (on 64-bit Ubuntu 16.04).
Staring the Arduino IDE, I've selected the correct board (Tools>>Board>>BSFrance>>LoRA32u4).
I've selected the correct port Tools>>Port>>/dev/ttyACM1 (LoRA32u4).
Verifying a trivial sketch looks fine:
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

Result:
Sketch uses 4104 bytes (14%) of program storage space. Maximum is 28672 bytes.
Global variables use 149 bytes of dynamic memory.

The USB device appears in lsusb as: Bus 002 Device 077: ID 239a:800c.
Clicking install causes a white LED to flicker for around ten seconds, but results in:
avrdude: error: buffered memory access not supported. Maybe it isn't
a butterfly/AVR109 but a AVR910 device?
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

or:
Couldn't find a Board on the selected port. Check that you have the
correct port selected.  If it is correct, try pressing the board's reset 
button after initiating the upload.

or:
Found programmer: Id = "CATERIN"; type = 

or:
Device code: 0x0d

or:
.   Software Version = 1.0; Hardware Version = 

or:
An error occurred while uploading the sketch

How do I transfer code onto this board?
(I am new to Arduino, so I may be missing something obvious.  I do have lots of experience programming vanilla ATMEGAs in C without the Arduino IDE.)
--
I have an AVRISP mkII - would burning a new boot-loader help, or just wreck the USB-serial on the device?

user51238: I've had the same problem, but couldn't fix it with the "Upload using programmer".
Instead i sound that the problem was that the serial connection kept dropping after a couple of seconds. My colleague, also on Ubuntu, had the same issue.
This fixed it for me: https://learn.adafruit.com/adafruit-arduino-ide-setup/linux-setup#udev-rules
The board registers as an Adafruit board on my system, and apparently the ModemManager is not too keen on that. 
After running first command in the link and restarting, i could upload to the board from Arduino IDE with no errors.

42159: <p>I've bought a BSFrance LoRA32u4 from DIYmall on eBay UK.</p>

<p><a href="https://bsfrance.fr/lora-long-range/1311-BSFrance-LoRa32u4-1KM-Long-Range-Board-Based-Atmega32u4-433MHz-LoRA-RA02-Module.html" rel="nofollow noreferrer">https://bsfrance.fr/lora-long-range/1311-BSFrance-LoRa32u4-1KM-Long-Range-Board-Based-Atmega32u4-433MHz-LoRA-RA02-Module.html</a></p>

<p>I've copied the "bsfrance" directory (from the ZIP) into Arduino/hardware (on 64-bit Ubuntu 16.04).</p>

<p>Staring the Arduino IDE, I've selected the correct board (Tools>>Board>>BSFrance>>LoRA32u4).</p>

<p>I've selected the correct port Tools>>Port>>/dev/ttyACM1 (LoRA32u4).</p>

<p>Verifying a trivial sketch looks fine:</p>

<pre><code>void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}
</code></pre>

<p>Result:</p>

<pre><code>Sketch uses 4104 bytes (14%) of program storage space. Maximum is 28672 bytes.
Global variables use 149 bytes of dynamic memory.
</code></pre>

<p>The USB device appears in <code>lsusb</code> as: <code>Bus 002 Device 077: ID 239a:800c</code>.</p>

<p>Clicking install causes a white LED to flicker for around ten seconds, but results in:</p>

<pre><code>avrdude: error: buffered memory access not supported. Maybe it isn't
a butterfly/AVR109 but a AVR910 device?
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.
</code></pre>

<p>or:</p>

<pre><code>Couldn't find a Board on the selected port. Check that you have the
correct port selected.  If it is correct, try pressing the board's reset 
button after initiating the upload.
</code></pre>

<p>or:</p>

<pre><code>Found programmer: Id = "CATERIN"; type = 
</code></pre>

<p>or:</p>

<pre><code>Device code: 0x0d
</code></pre>

<p>or:</p>

<pre><code>.   Software Version = 1.0; Hardware Version = 
</code></pre>

<p>or:</p>

<pre><code>An error occurred while uploading the sketch
</code></pre>

<p>How do I transfer code onto this board?</p>

<p>(I am new to Arduino, so I may be missing something obvious.  I do have lots of experience programming vanilla ATMEGAs in C without the Arduino IDE.)</p>

<p>--</p>

<p>I have an AVRISP mkII - would burning a new boot-loader help, or just wreck the USB-serial on the device?</p>
 51238: <p>I've had the same problem, but couldn't fix it with the "Upload using programmer".
Instead i sound that the problem was that the serial connection kept dropping after a couple of seconds. My colleague, also on Ubuntu, had the same issue.</p>

<p>This fixed it for me: <a href="https://learn.adafruit.com/adafruit-arduino-ide-setup/linux-setup#udev-rules" rel="nofollow noreferrer">https://learn.adafruit.com/adafruit-arduino-ide-setup/linux-setup#udev-rules</a></p>

<p>The board registers as an Adafruit board on my system, and apparently the ModemManager is not too keen on that. </p>

<p>After running first command in the link and restarting, i could upload to the board from Arduino IDE with no errors.</p>
