Scale up pages that area smaller than the paper.
void pdfPrintExpandSmallPages(PDFHandle pdf, int expand)
If this function is called with expand = 1, pages that are smaller than the paper (or printable area) will be scaled up to fill the paper.

pdfPrintResetParams resets this to its default value of 0, which means to print pages smaller than the paper at actual size.

pdfPrintExpandSmallPages(pdf, 1);