Here is an example of the fit visible - fit width behavior by the
PSR-500 that I mentioned before. I made two trial PDF's both
the same page size 1.5 x 4 inches. One was scanned in and therefore
had no fonts. The size button had no useful effect - instead when
pushed the first page of the file was displayed.
The second contained a font - It was prepared from a word for windows
doc file - the page size was set in word to 1.5 x 4 inches with top
and bottom margins of 0.2 inch and left and right margins of 0.1 inch.
As instructed by Adobe see :
www.adobe.com/support/techdocs/330729.html
The same margins were set in adobe acrobat and a pdf created. When the
size button was pushed the display changed but all the print showed in
both views - doesn't really fit width unless you're referring in some
way to the fonts. See comparison picture.
Note in the illiad reader comparison picture - a bit of dust blew onto the displays.