Вы можете сделать что-то вроде этого:
Sub Tester()
'pass worksheet and a variable number of range addresses
AutoSumRanges ActiveSheet, "C3:C5", "C11:C15", "A1:A3"
End Sub
'add a SUM() beneatch each range, on the worksheet "ws"
Sub AutoSumRanges(ws As Worksheet, ParamArray ranges() As Variant)
Dim rng As Variant
For Each rng In ranges
With ws.Range(rng)
.Cells(.Cells.Count).Offset(1, 0).Formula = _
"=SUM(" & .Address(False, False) & ")"
End With
Next rng
End Sub