Scale up pages that area smaller than the paper.
[read/write property] expandSmallPages([out, retval] VARIANT_BOOL *expand) expandSmallPages([in] VARIANT_BOOL expand)
If this property is set to true, pages that are smaller than the paper (or printable area) will be scaled up to fill the paper.

resetParams resets this to its default value of false, which means to print pages smaller than the paper at actual size.

pdf.expandSmallPages = True