Acho que seria mais fácil usar o VBA instr
Desbaste, isso deve funcionar -
Sub Lokam()
Dim a As Range
Dim b As Range
For Each a In Range("A:A")
If a = "" Then Exit Sub
For Each b In Range("B:B")
If b = "" Then GoTo yay:
If InStr(a, b) > 0 Then
a.Offset(, 2) = a
End If
Next
yay:
Next
End Sub