I have a macro that opens a file to use for VLOOKUP function. I start in original file, ask user for file to use and I want to execute the function in my original file, not the file I opened

fName = Application.GetOpenFilenam
Workbooks.Open fNam

Range("N2").Selec
ActiveCell.FormulaR1C1 =
"=VLOOKUP(RC[-13],'[fName]Qty-Value'!$A:$C,2,FALSE)

I think I need something before this to capture the name of the original file/worksheet, so I can get back to it before I execute the formula