Declaration of the National Anti-Slavery Convention was written by William Lloyd Garrison for the formation of the American Anti-Slavery Society in December 1833. It was reprinted in The Liberator on December 14, 1833. It is now available in the Public Domain.
You can also use the Optimized PDF option to crank the size down in very targeted ways. Given the big before/after shift, the culprit is probably the image you're embedding. Try exporting that file in various formats (PDF, jpg, png) and then import it.
1 Use transform tools to change the image's orientation. 2  Change the visible portion of the image using the Crop tool. 3  Select and replace an existing image, or add a new image. 4  Export an image for editing and instant updating in your PDF file. Change the visible portion of the image using the Crop tool. 2  Select and replace an existing image, or add a new image. 3  Export an image for editing and instant updating in your PDF file.