''' <summary>
''' Loads PDF document from a stream, adds page to PDF document and
''' saves changes back to the source stream.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
Public Shared Sub OpenChangeAndSavePdfDocumentFromStream(pdfFilename As String)
    ' open stream
    Using stream As System.IO.Stream = System.IO.File.Open(pdfFilename, System.IO.FileMode.Open, System.IO.FileAccess.ReadWrite)
        ' open PDF document
        Using document As New Vintasoft.Imaging.Pdf.PdfDocument(stream)
            ' add new page to PDF document
            document.Pages.Add(Vintasoft.Imaging.PaperSizeKind.A4)

            ' save changes to the source stream
            document.SaveChanges()
        End Using

        ' close the stream
        stream.Close()
    End Using
End Sub

/// <summary>
/// Loads PDF document from a stream, adds page to PDF document and
/// saves changes back to the source stream.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
public static void OpenChangeAndSavePdfDocumentFromStream(string pdfFilename)
{
    // open stream
    using (System.IO.Stream stream = System.IO.File.Open(
        pdfFilename, System.IO.FileMode.Open, System.IO.FileAccess.ReadWrite))
    {
        // open PDF document
        using (Vintasoft.Imaging.Pdf.PdfDocument document = 
            new Vintasoft.Imaging.Pdf.PdfDocument(stream))
        {
            // add new page to PDF document
            document.Pages.Add(Vintasoft.Imaging.PaperSizeKind.A4);

            // save changes to the source stream
            document.SaveChanges();
        }

        // close the stream
        stream.Close();
    }
}