using (PdfDocument pdf = PdfDocument.Open(fullname))
{
    PdfDocumentBuilder builder = new PdfDocumentBuilder { };
    PdfDocumentBuilder.AddedFont font = builder.AddStandard14Font(Standard14Font.Helvetica);

    PdfPageBuilder pageBuilder = builder.AddPage(pdf, 1);  
    pageBuilder.SetStrokeColor(0, 255, 0);

    pageBuilder.AddText("TEST Y=-20", 6, new PdfPoint(50, -20), font);
    pageBuilder.AddText("TEST X=0,Y=0", 6, new PdfPoint(0, 0), font);
    pageBuilder.AddText("TEST X=-20", 6, new PdfPoint(-20, 20), font);
    pageBuilder.AddText("TEST X=-50", 6, new PdfPoint(-50, 50), font);
    pageBuilder.AddText("TEST X=-100", 6, new PdfPoint(-100, 100), font);
    pageBuilder.AddText("TEST X=-200", 6, new PdfPoint(-200, 200), font);
    pageBuilder.AddText("TEST X=-300", 6, new PdfPoint(-300, 300), font);
    pageBuilder.AddText("TEST X=-400", 6, new PdfPoint(-400, 400), font);
    pageBuilder.AddText("TEST X=-450", 6, new PdfPoint(-450, 450), font);
}