private void convertToPdfButton_Click(object sender, EventArgs e)
{
    // Create a HTML to PDF converter object with default settings
    HtmlToPdfConverter htmlToPdfConverter = 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=";

    Cursor = Cursors.WaitCursor;

    string outPdfFile = @"DemoAppFiles\Output\HTML_to_PDF\Partially_Convert_HTML.pdf";
    try
    {
        byte[] outPdfBuffer = null;
                
        if (convertElementRadioButton.Checked)
        {
            // Select the HTML element to convert
            string htmlElementSelector = htmlElementSelectorTextBox.Text;
            htmlToPdfConverter.RenderedHtmlElementSelector = htmlElementSelector;
        }

        // Convert the HTML page to a PDF document in a memory buffer
        outPdfBuffer = htmlToPdfConverter.ConvertUrl(urlTextBox.Text);

        // Write the memory buffer in a PDF file
        System.IO.File.WriteAllBytes(outPdfFile, outPdfBuffer);
    }
    catch (Exception ex)
    {
        // The HTML to PDF conversion failed
        MessageBox.Show(String.Format("HTML to PDF Error. {0}", ex.Message));
        return;
    }
    finally
    {
        Cursor = Cursors.Arrow;
    }

    // Open the created PDF document in default PDF viewer
    try
    {
        System.Diagnostics.Process.Start(outPdfFile);
    }
    catch (Exception ex)
    {
        MessageBox.Show(String.Format("Cannot open created PDF file '{0}'. {1}", outPdfFile, ex.Message));
    }
}