PDF Mosaic: How to add Push button to PDF document

using PDFMosaic;
using System;
 
namespace Buttons
{
    class Buttons
    {
        static void Main()
        {
            PDFDocument doc = new PDFDocument();
            PDFPage page = new PDFPage(PDFPaperFormat.A4);
 
            PDFPushButton button = new PDFPushButton(10, 40, 100, 30, "btn1");
            button.Caption = "Button";
 
            page.Annotations.Add(button);
            doc.Pages.Add(page);
 
            doc.Save("Buttons.pdf", true);
        }
    }
}