try this:
Sub YAY()
Dim LastRow As Long
Dim Path1 As String
Dim Msg As String
Msg = "Please Insert Path 1"
Path1 = Application.InputBox(Msg)
' find last row of column A
LastRow = FindLastRow(ActiveSheet, "A")
ActiveSheet.Range("F1:F" & LastRow).Value = Path1
End Sub
Public Function FindLastRow(ByVal WS As Worksheet, ColumnLetter As String) As Long
' this function will find the last row of the worksheet and column that you
' request
FindLastRow = WS.Range(ColumnLetter & Rows.Count).End(xlUp).Row
End Function