Option Explicit
Sub test()
Dim c As Range
With Sheets("Feuil2")
Set c = .Range("A2:A" & .Range("A65536").End(xlUp).Row).Find(Sheets("Feuil1").Range("A1").Value, , xlValues, xlWhole, , , False)
If Not c Is Nothing Then
Sheets("Feuil1").Rows(1).Copy .Rows(c.Row)
Else
Sheets("Feuil1").Rows(1).Copy .Rows(.Range("A65536").End(xlUp).Row + 1)
End If
End With
End Sub