How to create user defined paper sizes - HP and Photoshop CS3 CS4
For Red River Paper greeting cards, scrapbook 12x12 sheets, panorama printing, and other special projects, you need to define a custom paper size in the HP printer properties. Below are instructions for setting a custom paper size starting in Photoshop.
* Important Tip - the smaller paper dimension is ALWAYS the width. The larger dimension is always the height.