I just copied the Display line from the built-in apps and pasted it into the Qpdf file. All the desktop icons are in /home/QtPalmtop/apps/Applications. The line looks like this:
Display=640x480,144dpi,480x640,144dpi
edit: There\'s an easier way to do this. If you tap and hold the icon, a screen comes up where you can disable the magnification.