code: public PageStamp createPageStamp(PdfImportedPage iPage) {
          int pageNum = iPage.getPageNumber();
          PdfReader reader = iPage.getPdfReaderInstance().getReader();
          PdfDictionary pageN = reader.getPageN(pageNum);
          return new PageStamp(reader, pageN, this);
      }
docs: Create a page stamp. New content and annotations, including new fields, are allowed.
  The fields added cannot have parents in another pages. This method modifies the PdfReader instance.<p>
  The general usage to stamp something in a page is:
  <p>
  <pre>
  PdfImportedPage page = copy.getImportedPage(reader, 1);
  PdfCopy.PageStamp ps = copy.createPageStamp(page);
  ps.addAnnotation(PdfAnnotation.createText(copy, new Rectangle(50, 180, 70, 200), "Hello", "No Thanks", true, "Comment"));
  PdfContentByte under = ps.getUnderContent();
  under.addImage(img);
  PdfContentByte over = ps.getOverContent();
  over.beginText();
  over.setFontAndSize(bf, 18);
  over.setTextMatrix(30, 30);
  over.showText("total page " + totalPage);
  over.endText();
  ps.alterContents();
  copy.addPage(page);
  </pre>
  @param iPage an imported page
  @return the <CODE>PageStamp</CODE>