If my excel file is set up as follows:

Column B: old file source
Column F: new file source

Where do I make adjustments to snb's code? And does it rename all files until an empty row? 

Sub M_snb()
    sn = Cells(1, 2).Resize(Cells(Rows.Count, 2).End(xlUp).Row, 2)
     
    For j = 1 To UBound(sn)
        If Dir(sn(j, 1), 16) <> "" And Dir(sn(j, 2), 16) = "" Then Name sn(j, 1) As sn(j, 2)
    Next
End Sub