Ok, I see how I can make 8.5 x 11 PDF's of everything from Word documents to Photos in OSX, but how do I make a PDF of something from, say, PhotoShop that is 3"x4". I am trying to make a real simple print ad in PhotoShop (I know I should use a proper layout app) and rip it to PDF, but the ad is small, and when it goes to PDF, the ad is in the middle of a 8.5 x 11 PDF. Any tips on how I can get it the right size? Do I need to buy Acrobat for OSX? Thanks.