Public myFontB As New Font("Verdana", 8, FontStyle.Bold)
    Public myFontR As New Font("Verdana", 8, FontStyle.Regular)
    Public myFontI As New Font("Verdana", 8, FontStyle.Italic)
    Public myFontU As New Font("Verdana", 8, FontStyle.Underline)

...
            scrollRichText("gefundene Werte: ", myFontB, Color.Gray, _
              rich_LOG.Lines.Length)
...
oder 
 
 scrollRichText(clsKalender.myCalendar, myFontI, Color.Red, _
   rich_LOG.Lines.Length)

    Function scrollRichText(ByVal neuerText As String, _
                            ByVal myStyle As Font, _
                            ByVal myColor As Color, _
                            ByVal cRow As Integer) As String
 
        Me.rich_LOG.Text = Me.rich_LOG.Text & neuerText & vbCrLf
        Me.rich_LOG.SelectionStart = Me.rich_LOG.TextLength - 1
 
        'http://msdn.microsoft.com/de-de/library/system.windows.forms.richtextb
        ' ox.aspx
        'Stop
        ' Debug.WriteLine(Form1.rich_LOG.SelectionStart)
        Debug.WriteLine("Start:" & Me.rich_LOG.GetFirstCharIndexFromLine(cRow))
 
        If cRow = 0 Then
            Debug.WriteLine("Länge:" & Me.rich_LOG.Lines(cRow).Length)
        Else
            Debug.WriteLine("Länge:" & Me.rich_LOG.Lines(cRow).Length)
        End If
 
        Me.rich_LOG.Select(Me.rich_LOG.GetFirstCharIndexFromLine(cRow), _
          Me.rich_LOG.Lines(cRow).Length) ' Von Index, Länge
        Me.rich_LOG.SelectionColor = myColor
        Me.rich_LOG.SelectionFont = myStyle 'New Font("Courier", _
          Form1.rich_LOG.Font.Size, FontStyle.Bold Or FontStyle.Italic) ' Fett 
        ' und Kursiv, Größe wie bisher
        Me.rich_LOG.ScrollToCaret()
    End Function