Public Class Form1
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        RTF1.LoadFile("D:\test.rtf")
        PictureBox1.Image = Screenshot(RTF1)
End Sub
 
 
Public Function Screenshot(ByVal Ctrl As Control) As Bitmap
 
        Dim w As Integer = Ctrl.Width  ' Breite des Controls / der Form
        Dim h As Integer = Ctrl.Height ' Höhe des Controls / der Form
 
        Screenshot = New Bitmap(w, h)
        Ctrl.DrawToBitmap(Screenshot, Rectangle.FromLTRB(0, 0, w, h))
        Return Screenshot
 
End Function
 
 
End Class