using var dwimg = (DwfImage)Image.Load(file);

CadRasterizationOptions rasterizationOptions = new CadRasterizationOptions();
rasterizationOptions.DrawType = CadDrawTypeMode.UseObjectColor;

PdfOptions pdfOptions = new PdfOptions();
pdfOptions.VectorRasterizationOptions = rasterizationOptions;

DwfWhipText text = new DwfWhipText();
text.Color = Color.Red;
text.Text = new CAD.FileFormats.Dwf.Whip.Objects.DwfString("THIS IS A TEST TEXT");
text.Position = new CAD.FileFormats.Dwf.Whip.Objects.DwfWhipLogicalPoint(40000, 70000);
text.Font = new CAD.FileFormats.Dwf.Whip.Objects.Service.DwfWhipFont();
text.Font.Name = new CAD.FileFormats.Dwf.Whip.Objects.Service.Font.DwfWhipOptionFontName();
text.Font.Name.Value = new CAD.FileFormats.Dwf.Whip.Objects.DwfString("times new roman");
text.Font.Height = new CAD.FileFormats.Dwf.Whip.Objects.Service.Font.DwfWhipOptionFontHeight();
text.Font.Height.Value = 2000;
text.IsVisible = true;

dwimg.AddElement(0, text);
image.Save(outFileAdded, pdfOptions);

dwimg.RemoveElement(0, count);
image.Save(outFileAdded, pdfOptions);