How difficult is it to rescale models from a PDF file theres several kits I'd like to rescale just changing the print size isn't an option as I'd like all the parts to be on only one sheet (I know if I try to rescale a kit with out knowing this it will just end up with the key bit in half on two different sheets). Any advice I'm a graphics program novice so simple explanations would be necessary. Better still is there a good beginners how to guide about?