Sub TestFormula()
Dim LastRow As Long
LastRow = Cells(Rows.Count, "A").End(xlUp).Row
Range("C2:C" & LastRow).Formula = "=IFERROR(INDEX(Feuil2!C1:C677,MATCH(RC1,Feuil2!C2,0),MATCH(R1C,Feuil2!R1C1:R1C52,0)),"""")"
Range("D2:D" & LastRow).Formula = "=IFERROR(INDEX(Feuil2!C1:C677,MATCH(RC1,Feuil2!C2,0),MATCH(R1C,Feuil2!R1C1:R1C52,0)),"""")"
End Sub