Sub Ajout_Colonnes()
Dim col As Long
col = Cells(2, Columns.Count).End(xlToLeft).Column
'col = Rows("2:2").Find(What:="z").Column
Range("F1").Select
Selection.UnMerge
Columns("K:L").Copy
Columns(col).Insert Shift:=xlToRight
col = Cells(2, Columns.Count).End(xlToLeft).Column
Range(Range("F1"), Cells(1, col)).Merge
End Sub