Need code to enter the last cell when using VLOOKUP

[Footley]

I need the following code modified so the lookup range is dynamic. The next file may not be the same size.
The first line is how it appears in the cell.
The second line is in the VBA code.
All data will be in columns A and B but the number of rows changes.

 =VLOOKUP(C2,Order!$A$2:$B$261,2,FALSE)    

ActiveCell.FormulaR1C1 = "=VLOOKUP(RC[2],Order!R2C1:R261C2,2,FALSE)"