rtf.Text = "+49 8458387"
 
   rtf.SelectionStart = 8
   rtf.SelectionLength = 0
   rtf.SelectedText = "--"
 
   rtf.SelectionStart = 10
   rtf.SelectionLength = 3
   rtf.SelectionColor = Color.Red
 
   'alternative Hervorhebung
   'rtf.SelectionFont = New System.Drawing.Font _
   '(rtf.Font.Name, rtf.Font.Size + 2, FontStyle.Italic)