The print size is already implemented in pictures but to thoose of you who don't know how to use it...
Each page has 215,8 x 279,39 mm.
Hey btw the usual A4 has 210 x 297. I gues in v1.0 I'll try to pack it a little bit so each page will be smaller than A4 and i will add an instructions "how to" with what margin set to print ;)