MultiframeImageWatermarkOptions

public class MultiframeImageWatermarkOptions : WatermarkOptions

ImageLoadOptions loadOptions = new ImageLoadOptions();
using (Watermarker watermarker = new Watermarker(@"C:\test.gif", loadOptions))
{
    TextWatermark watermark = new TextWatermark("Test", new Font("Arial", 12));

    MultiframeImageWatermarkOptions options = new MultiframeImageWatermarkOptions();
    options.FrameIndex = 0;

    watermarker.Add(watermark, options);
    watermarker.Save();
}