This sample code demonstrates how to set URL link to rectangle text area in the existing PDF document
This example teaches how to open existing PDF and set hyperlink URL to the rectangle area in text and then save modified PDF as new using ByteScout PDF SDK for NET

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 create URI (link) action.
''' </summary>
Class Program

    Shared Sub Main()

        ' Create new document
        Dim pdfDocument = New Document()
        pdfDocument.RegistrationName = "demo"
		pdfDocument.RegistrationKey = "demo"
        ' Add page
        Dim page = New Page(PaperFormat.A4)
        pdfDocument.Pages.Add(page)

        ' Add button
        Dim button = New PushButton(20, 20, 150, 25, "button1")
        button.Caption = "BYTESCOUT.COM"
        ' Add URI action
        Dim action = New URIAction(New Uri("http://bytescout.com/"))
        button.OnActivated = action
        page.Annotations.Add(button)

        ' 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;
using System.Diagnostics;
using Bytescout.PDF;

namespace UriAction
{
	/// <summary>
	/// This example demonstrates how to create URI (link) action.
	/// </summary>
	class Program
	{
		static void Main()
		{
			// Create new document
			Document pdfDocument = new Document();
			pdfDocument.RegistrationName = "demo";
			pdfDocument.RegistrationKey = "demo";
			// Add page
			Page page = new Page(PaperFormat.A4);
			pdfDocument.Pages.Add(page);

			// Add button
			PushButton button = new PushButton(20, 20, 150, 25, "button1");
			button.Caption = "BYTESCOUT.COM";
			// Add URI action
			URIAction action = new URIAction(new Uri("http://bytescout.com/"));
			button.OnActivated = action;
			page.Annotations.Add(button);
			
			// Save document to file
			pdfDocument.Save("result.pdf");

			// Cleanup 
			pdfDocument.Dispose();

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