Great!
Please add your findings to our wiki.librecad.org , user manual sounds good.
rfritz wrote
This is the procedure I have worked out:
1. Draw the border.
1a. The border has to be centered within the finished page, or this will not work.
1b. For my current small page, I am using a 10" x 7.5" border, which is half an inch within a US "letter size" page.
1c. There must be nothing outside the border, or LibreCAD will use it to center the page, rather than the border.
2. Select print preview. This will produce a preview centered to the page, and scaled so that the border is as large as possible.
3. Set the scale and check "fixed."
4. Press the center button.
5. Print.