The default page size is often the one you'll want to use. However it may be that your PDFs are required to conform to a particular page size. The table below gives common paper sizes and dimensions for quick reference.

The default size is Letter.

	Paper Size		Width in Points		Height in Points
	A3		842		1190
	A4		595		842
	A5		420		595
	B4		729		1032
	B5		516		729
	Letter		612		792
	Legal		612		1008
	Tabloid		792		1224
	Ledger		1224		792
	Statement		396		612
	Executive		540		720
	Folio		612		936
	Quarto		610		780
	10x14		720		1008

To change the page size you should use the MediaBox property.