The example demonstrates how to load and modify an existing document using ByteScout PDF SDK.

Program.vb:
VB

'*******************************************************************
'       ByteScout PDF SDK
'                                                                   
'       Copyright © 2016 Bytescout, http://www.bytescout.com        
'       ALL RIGHTS RESERVED                                         
'                                                                   
'*******************************************************************

Imports Bytescout.PDF

''' <summary>
''' This example demonstrates how to load and modify an existing document.
''' </summary>
Class Program

    Shared Sub Main()

        ' Create new Document object
        Dim pdfDocument = New Document()
        pdfDocument.RegistrationName = "demo"
		pdfDocument.RegistrationKey = "demo"

        '  Load existing document
        pdfDocument.Load("sample.pdf")

        ' Add new page to loaded document
        Dim page As New Page(PaperFormat.A4)
        Dim font As New Font(StandardFonts.Times, 24)
        Dim brush As New SolidBrush()
        page.Canvas.DrawString("New Page", font, brush, 20, 20)
        pdfDocument.Pages.Add(page)

        ' Save document to file
        pdfDocument.Save("result.pdf")

        ' Cleanup 
		pdfDocument.Dispose()

        ' Open document in default PDF viewer app
        Process.Start("result.pdf")

    End Sub

End Class 

Program.cs:
C#

//*******************************************************************
//       ByteScout PDF SDK		                                     
//                                                                   
//       Copyright © 2016 ByteScout - http://www.bytescout.com       
//       ALL RIGHTS RESERVED                                         
//                                                                   
//*******************************************************************

using System.Diagnostics;
using Bytescout.PDF;

namespace LoadDocument
{
	/// <summary>
	/// This example demonstrates how to load and modify an existing document.
	/// </summary>
	class Program
	{
		static void Main()
		{
			// Create new Document object
			Document pdfDocument = new Document();
			pdfDocument.RegistrationName = "demo";
			pdfDocument.RegistrationKey = "demo";
			
			// Load existing document
			pdfDocument.Load("sample.pdf");
			
			// Add new page to loaded document
			Page page = new Page(PaperFormat.A4);
			Font font = new Font(StandardFonts.Times, 24);
			Brush brush = new SolidBrush();
			page.Canvas.DrawString("New Page", font, brush, 20, 20);
			pdfDocument.Pages.Add(page);
			
			// Save document to file
			pdfDocument.Save("result.pdf");

			// Cleanup 
			pdfDocument.Dispose();

			// Open document in default PDF viewer app
			Process.Start("result.pdf");
		}
	}
}