Adds a rubber stamp annotation: name in capitals in a rounded frame, filling rect.
public PdfStampAnnotation AddStampAnnotation(PdfRectangle rect, string name, PdfAnnotationOptions? options = null)
The stamp's rectangle in default user space.
The icon name (Name), one of Table 184's (such as Approved, NotApproved, Draft) or another; its words are the stamp's text.
Colour, width, flags and markup texts; null for red.
ISO 32000-2 §12.5.6.12, Table 184 (PDF 1.3).