Add Checkbox in PDF using C# | Insert check boxes in PDF

add-checkbox-pdf.cs

using (GroupDocs.Annotation.Annotator annotator = new GroupDocs.Annotation.Annotator("input.pdf"))
{
    GroupDocs.Annotation.Models.FormatSpecificComponents.Pdf.CheckBoxComponent checkbox = new GroupDocs.Annotation.Models.FormatSpecificComponents.Pdf.CheckBoxComponent
    {
        Checked = true,
        Box = new GroupDocs.Annotation.Models.Rectangle(100, 100, 100, 100),
        PenColor = 65535,
        Style = GroupDocs.Annotation.Models.BoxStyle.Star,
        Replies = new List<GroupDocs.Annotation.Models.Reply>
{
    new GroupDocs.Annotation.Models.Reply
    {
        Comment = "First comment",
        RepliedOn = DateTime.Now
    },
    new GroupDocs.Annotation.Models.Reply
    {
        Comment = "Second comment",
        RepliedOn = DateTime.Now
    }
}
    };
    annotator.Add(checkbox);
    annotator.Save("checkbox.pdf");
}