user53628: I tried to upload sketch to my RFDuino. I can select the RFDuino port. But I can't upload cos I can't select the RFDuino board.
I followed the installation steps listed here
but I don't see RFduino package in Board Manager after I finished the steps above. 
I am using Mac Mojave and Arduino IDE v1.8.9. I have tried it with v1.6.6 but results the same.

user57663: Turns out that rfduino.com's domain is gone, so the link will always return with an error downloading. After reading this thread arduino.cc, @pert posted a link for the .json file that used to be at the website you have. I used this link on MacOS Mojave and Arduino v1.8.9 and it worked perfectly!

53628: <p>I tried to upload sketch to my RFDuino. I can select the RFDuino port. But I can't upload cos I can't select the RFDuino board.</p>

<p>I followed the installation steps listed <a href="https://github.com/RFduino/RFduino" rel="nofollow noreferrer">here</a>
but I don't see RFduino package in Board Manager after I finished the steps above. </p>

<p>I am using Mac Mojave and Arduino IDE v1.8.9. I have tried it with v1.6.6 but results the same.</p>
 57663: <p>Turns out that rfduino.com's domain is gone, so the link will always return with an error downloading. After reading this thread <a href="https://forum.arduino.cc/index.php?topic=610331.0" rel="nofollow noreferrer">arduino.cc</a>, @pert posted <a href="https://gist.github.com/per1234/f7822073e05276c4243740eaab4235d1/raw/9c34051294ddd54dbbdf3bec392df0afef8da938/package_rfduino166_index.json" rel="nofollow noreferrer">a link for the .json file</a> that used to be at the website you have. I used this link on MacOS Mojave and Arduino v1.8.9 and it worked perfectly!</p>
