VBA to copy formulas in column D and paste as values in same column

I have create a formula in column D. Once the formula is created, I want to copy and paste as values. I am try to make the code more efficient by not having select the cells in the process. I've tried both methods below, but can't get either to work. Thanks

Range("D2:D" & Lastrow).FormulaR1C1 = "=IF(LEFT(RC[8],3)=""TEN"",""RR-12"","""")"
Range("D2:D" & Lastrow) = Range("D2:2" & Lastrow).Value

Range("D2:D" & Lastrow).FormulaR1C1 = "=IF(LEFT(RC[8],3)=""TEN"",""RR-12"","""")"
Columns("D:D").copy Destination:=Columns("D:D")Paste:=xlPasteValues