Check out this thread:
https://www.mobileread.com/forums/sho...?threadid=9562
for recommendations on formatting PDF's for the Reader. Section III of the PDF file attached to the first post should help you out.
If for some reason that doesn't work you could use the PowerPoint "Save as jpg" option to save the slides as images - clunky, but it might work as a backup.
Good luck and welcome aboard!
Bob