arrowannotation.cs

using (Annotator annotator = new Annotator("input.pdf"))
{
    ArrowAnnotation arrow = new ArrowAnnotation
    {
        Box = new Rectangle(100, 100, 100, 100),
        CreatedOn = DateTime.Now,
        Message = "This is arrow annotation",
        Opacity = 0.7,
        PageNumber = 0,
        PenColor = 65535,
        PenStyle = PenStyle.Dot,
        PenWidth = 3,
        Replies = new List<Reply>
        {
            new Reply
            {
                Comment = "First comment",
                RepliedOn = DateTime.Now
            },
            new Reply
            {
                Comment = "Second comment",
                RepliedOn = DateTime.Now
            }
        }
    };
    annotator.Add(arrow);
    annotator.Save("result.pdf");
}