Protected Sub convertToPdfButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    ' Create a HTML to PDF converter object with default settings
    Dim htmlToPdfConverter As New HtmlToPdfConverter()

    ' Set license key received after purchase to use the converter in licensed mode
    ' Leave it not set to use the converter in demo mode
    htmlToPdfConverter.LicenseKey = "fvDh8eDx4fHg4P/h8eLg/+Dj/+jo6Og="

    ' Set the PDF file to be inserted before conversion result
    Dim pdfFileBefore As String = Server.MapPath("~/DemoAppFiles/Input/PDF_Files/Merge_Before_Conversion.pdf")
    htmlToPdfConverter.PdfDocumentOptions.AddStartDocument(pdfFileBefore)

    ' Set the PDF file to be added after conversion result
    Dim pdfFileAfter As String = Server.MapPath("~/DemoAppFiles/Input/PDF_Files/Merge_After_Conversion.pdf")
    htmlToPdfConverter.PdfDocumentOptions.AddEndDocument(pdfFileAfter)

    ' The URL to convert
    Dim url As String = urlTextBox.Text

    ' Convert the HTML page to a PDF document and add the external PDF documents
    Dim outPdfBuffer() As Byte = htmlToPdfConverter.ConvertUrl(url)

    ' Send the PDF as response to browser

    ' Set response content type
    Response.AddHeader("Content-Type", "application/pdf")

    ' Instruct the browser to open the PDF file as an attachment or inline
    Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Merge_HTML_with_Existing_PDF.pdf; size={0}", outPdfBuffer.Length.ToString()))

    ' Write the PDF document buffer to HTTP response
    Response.BinaryWrite(outPdfBuffer)

    ' End the HTTP response and stop the current page processing
    Response.End()
End Sub