GifImageWatermarkOptions

public sealed class GifImageWatermarkOptions : MultiframeImageWatermarkOptions

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

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

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