code: public void setPageSize(Rectangle pageSize) {
          if(!guessFormat(pageSize, false)) {
              this.pageWidth = (int) (pageSize.getWidth() * RtfElement.TWIPS_FACTOR);
              this.pageHeight = (int) (pageSize.getHeight() * RtfElement.TWIPS_FACTOR);
              this.landscape = pageWidth > pageHeight;
          }
      }
docs: Set the page size to use. This method will use guessFormat to try to guess the correct
  page format. If no format could be guessed, the sizes from the pageSize are used and
  the landscape setting is determined by comparing width and height;
  
  @param pageSize The pageSize to use