This will automatically populate your range in one go. You need not to go for selection autofill post that and i designed this macro basis of your existing data..and in it its b column..so the macro will become...
Saurabh...
1: 2: 3:
Windows("Book1.xls").Activate Range("b2:b" & Cells(65536, "A").End(xlUp).Row).Select Selection.Formula = "=IF(ISNA(VLOOKUP(A2,Sheet2!A:B,2,0)),""-"",VLOOKUP(A2,Sheet2!A:B,2,0))"