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=";
            
    // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2;

    // Enable footer in the generated PDF document
    htmlToPdfConverter.PdfDocumentOptions.ShowFooter = true;

    // Optionally add a space between footer and the page body
    // Leave this option not set for no spacing
    htmlToPdfConverter.PdfDocumentOptions.BottomSpacing = float.Parse(footerSpacingTextBox.Text);

    // Set the footer height in points
    htmlToPdfConverter.PdfFooterOptions.FooterHeight = 50;

    // ----- Add HTML with Page Numbering to Footer -----

    // Create a variable HTML element with page numbering
    string htmlStringWithPageNumbers = htmlWithPageNumbersTextBox.Text;
    string baseUrl = baseUrlTextBox.Text;
    HtmlToPdfVariableElement footerHtmlWithPageNumbers = new HtmlToPdfVariableElement(htmlStringWithPageNumbers, baseUrl);

    // Set the HTML element to fit the container height
    footerHtmlWithPageNumbers.FitHeight = true;

    // Add variable HTML element with page numbering to footer
    htmlToPdfConverter.PdfFooterOptions.AddElement(footerHtmlWithPageNumbers);

    // Optionally draw a line at the top of the footer
    if (drawFooterLineCheckBox.Checked)
    {
        // Calculate the footer width based on PDF page size and margins
        float footerWidth = htmlToPdfConverter.PdfDocumentOptions.PdfPageSize.Width -
                    htmlToPdfConverter.PdfDocumentOptions.LeftMargin - htmlToPdfConverter.PdfDocumentOptions.RightMargin;
                
        // Create a line element for the top of the footer
        LineElement footerLine = new LineElement(0, 0, footerWidth, 0);

        // Set line color
        footerLine.ForeColor = Color.Gray;

        // Add line element to the bottom of the footer
        htmlToPdfConverter.PdfFooterOptions.AddElement(footerLine);
    }

    Cursor = Cursors.WaitCursor;

    // Convert HTML to PDF using the settings above
    string outPdfFile = @"DemoAppFiles\Output\HTML_to_PDF\Page_Numbers_in_HTML.pdf";
    try
    {
        // Convert the HTML page to a PDF document in a memory buffer
        byte[] 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));
    }
}