Dim zelle1 As String
Dim zelle2 As String
Dim actcell As Range
Dim zellnrF As Long
Dim Zellnract As Long
Dim zellnrL As Long
'Dim WS As Worksheet
Dim Formel As String
'WS = ActiveSheet.Name
zellnrF = InputBox("Bitte geben Sie die erste zu summierende zellenzeilenzahl" & _
  "ei ein (z.B. 87)")
zellenrL = Cells(Rows.Count, 1).End(xlUp).Row
MsgBox zellnrL
Zellnract = zellnrF
actcell = ("G" & zellnrF)
 
Cells(actcell).Select
zelle1 = Range("G" & zellnrF)
zelle2 = Range("F" & Zellnract)
Formel = "=SUMME(zelle1: zelle2)+ Summe(F1:F2)"
Cells(actcell).Formula = Formel
While Zellnract <= zellenrL

Gruß Armin

P.S.: always look on the bright side of Life!