''' <summary>
''' Creates the PDF documenet with circle annotation.
''' </summary>
''' <param name="outputPdfFilename">The output PDF filename.</param>
Public Shared Sub CreatePdfCircleAnnotation(outputPdfFilename As String)
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(outputPdfFilename, Vintasoft.Imaging.Pdf.PdfFormat.Pdf_14)
        Dim page As Vintasoft.Imaging.Pdf.Tree.PdfPage

        ' Add new page
        page = document.Pages.Add(Vintasoft.Imaging.PaperSizeKind.A4)
        page.Annotations = New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(document)
        Dim annotationRectangle As System.Drawing.RectangleF = page.MediaBox
        annotationRectangle.Inflate(-200, -300)

        ' Circle annotation
        Dim circle As New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfCircleAnnotation(page)
        circle.Rectangle = annotationRectangle
        circle.BorderWidth = 3
        circle.Padding = New Vintasoft.Imaging.PaddingF(circle.BorderWidth)
        circle.InteriorColor = System.Drawing.Color.Red
        circle.Color = System.Drawing.Color.Green
        circle.UpdateAppearance()
        page.Annotations.Add(circle)

        document.SaveChanges()
    End Using
End Sub

/// <summary>
/// Creates the PDF documenet with circle annotation.
/// </summary>
/// <param name="outputPdfFilename">The output PDF filename.</param>
public static void CreatePdfCircleAnnotation(string outputPdfFilename)
{
    using (Vintasoft.Imaging.Pdf.PdfDocument document = new Vintasoft.Imaging.Pdf.PdfDocument(
        outputPdfFilename, Vintasoft.Imaging.Pdf.PdfFormat.Pdf_14))
    {
        Vintasoft.Imaging.Pdf.Tree.PdfPage page;

        // Add new page
        page = document.Pages.Add(Vintasoft.Imaging.PaperSizeKind.A4);
        page.Annotations = new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(document);
        System.Drawing.RectangleF annotationRectangle = page.MediaBox;
        annotationRectangle.Inflate(-200, -300);

        // Circle annotation
        Vintasoft.Imaging.Pdf.Tree.Annotations.PdfCircleAnnotation circle = 
            new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfCircleAnnotation(page);
        circle.Rectangle = annotationRectangle;
        circle.BorderWidth = 3;
        circle.Padding = new Vintasoft.Imaging.PaddingF(circle.BorderWidth);
        circle.InteriorColor = System.Drawing.Color.Red;
        circle.Color = System.Drawing.Color.Green;
        circle.UpdateAppearance();
        page.Annotations.Add(circle);
        
        document.SaveChanges();
    }
}