Dim Filename As String = "C:\Test\Testfile.txt", _
            encoding As System.Text.Encoding = System.Text.Encoding.UTF8
 
      Dim contents() As String = System.IO.File.ReadAllLines(Filename, encoding)
 
      System.IO.File.AppendAllLines(Filename, contents, encoding)
 
      System.IO.File.WriteAllLines(Filename, contents, encoding)