PDF Mosaic: How to add caret annotation to PDF documents

using PDFMosaic;
using System;
 
namespace PDFCaretAnnotationSample
{
    class PDFCaretAnnotationSample
    {
        static void Main()
        {
            PDFDocument pdf = new PDFDocument();
			pdf = new PDFDocument();
            pdf.Pages.Add(new PDFPage(PDFPaperFormat.A4));
            PDFCaretAnnotation annot = new PDFCaretAnnotation(10, 10, 20, 20);
            annot.Color = new PDFColorRGB(0, 0, 0);
            annot.Symbol = PDFCaretSymbol.Paragraph;
            pdf.Pages[0].Annotations.Add(annot);
            annot = new PDFCaretAnnotation(40, 30, 20, 20);
            annot.Color = new PDFColorRGB(0, 255, 0);
            annot.Symbol = PDFCaretSymbol.None;
            pdf.Pages[0].Annotations.Add(annot);
            pdf.Save("TestCaretAnnotation.pdf", true);
        }
    }
}