Dim Str As String = DerAusgangsString
 
If Str.Length > 93 Then
   Dim Str1 As String = Str.Substring(0, 90) & Environment.NewLine
   Dim Str2 As String = Str.Substring(90, Str.Length - 90) & Environment.NewLine
   RTB1.AppendText(Str1)
   RTB1.SelectionIndent = 65
   RTB1.AppendText(Str2)
   RTB1.SelectionIndent = 0
Else
RTB1.AppendText(Str)
End If

Gruß
Christoph