Can I tell pdfposter what the printable area of a page is?

I'm trying to split a large PDF (it doesn't correspond to an exact paper size but a bit smaller than A2) into four A4 pages. pdfposter -m a4 -p 2x2a4 does this pretty well - except that the split pages are scaled so that they fill the paper right to the edge. When I then print them, the printer has a small non-printable area around the edge of the paper and I end up with small bits of the images missing.

Is there a way to tell pdfposter to shrink the pages slightly and leave an empty border around the page?