public MemoryStream UpdatePDFFromStream(MemoryStream ms)
{
    var exportMarkingText = "Company Proprietary. Copyright © The  Company";
    XFont font = new XFont("Calibri", 14, XFontStyle.Bold);
    PdfDocument PDFDoc = PdfReader.Open(ms, PdfDocumentOpenMode.Modify);
    for (int Pg = 0; Pg < PDFDoc.Pages.Count; Pg++)
    {
        PdfPage page = PDFDoc.Pages[Pg];
        XGraphics gfx = XGraphics.FromPdfPage(page);
        //check pdf's rotation angle
        var fileRotationAngle = PDFDoc.Pages[0].Rotate;
        XPoint point = new XPoint(0, 0);

        if (fileRotationAngle == 90)
        {
            point = new XPoint(60 - PDFDoc.Pages[0].Width, 50);
            gfx.RotateTransform(-fileRotationAngle);
        }
        else if ((fileRotationAngle == 0))
        {
            //point = new XPoint(60, 12);
            point = new XPoint(80, 12);

        }
        else
        {

        }
        XPoint pointFooter = new XPoint(80, 780);
        gfx.DrawString(exportMarkingText, font, XBrushes.Black, point);
        //sample test. will change as per user requirements
        gfx.DrawString("Not Valid after Sept-30-2024", font, XBrushes.Black, pointFooter);

    }
               
    PDFDoc.Save(ms);
    return ms;


}