To create reports using custom paper sizes, set the PaperSize property to custom, then set the CustomWidth and CustomHeight properties to the size of the page measured in twips.
If the PaperSize is set to a value other than custom, the paper size is determined by that setting. The CustomWidth and CustomHeight properties are not used in this case.
If the PaperSize is set to custom and the CustomWidth or CustomHeight properties are set to zero, the printer's default paper size is used.