How do i put an if statement to populate a cell with a formula

I want to use a vlookup nested an If statement that selects a formula based on a preceding column's(column A) value. There are multiple formulas listed in a table linked to the various values column A could have.

The goal is to look at column a and based on the value, insert the relavant formula to perform a check. I'm really kind of stumped after setting up the row to insert the formula. thanks

Sub Macro4()
Dim lastRow As Long
    lastRow = Range("Q" & Rows.Count).End(xlUp).Row