This was my first question upon joining the board too! If you haven't already found an answer, you can find the application
pdflrf in the first post in this thread:
https://www.mobileread.com/forums/showthread.php?t=13135
Under the list of file attachments, you likely want
pdflrfwin-0.99.zip. This solved the problem on the PDFs I was trying to view without even having to change from the default settings.