public static void Buil(Sitzung sitzung)
{
   Document document = BuildDocument(sitzung);

   DefineStyles(document);

   PdfDocumentRenderer renderer = new PdfDocumentRenderer(true, PdfFontEmbedding.Always)
   {
      Document = document
   };
   renderer.RenderDocument();

   PdfDocument pdfDocument = renderer.PdfDocument;
   PdfPage page = pdfDocument.Pages[0];
   AddFooter(page, userName);

   DocumentRenderer docRenderer = new DocumentRenderer(document);
   docRenderer.PrepareDocument();

   MemoryStream stream = new MemoryStream();
   pdfDocument.Save(stream);
}



public static void AddFooter(PdfPage page, string userName)
{
   XGraphics gfx = XGraphics.FromPdfPage(page);
   XRect rect = new XRect(new XPoint(), gfx.PageSize);
   rect.Inflate(-15, -20);

   XFont font = new XFont(Frutiger, 7, XFontStyle.Italic);
   XStringFormat format = new XStringFormat
   {
      Alignment = XStringAlignment.Near,
      LineAlignment = XLineAlignment.Far
   };
   gfx.DrawString($"Ausdruck von {userName} um {DateTime.Now.ToString("dd.MM.yyyy HH:mm")}", font, XBrushes.Black, rect, format);
}