Use a formula within a macro to extract data and copy down x number of rows

I'm trying to use a macro to insert a column into column P, then paste the following formula '= Mid(O2, Find("-", O2) + 1, Find("^^", Substitute(O2, "-", "^^", 2)) - Find("-", O2) - 1)' into cell P2. This formula extracts the data between 2 hyphens. I then would like this formula to be copied down, an X number of rows, which can be dependant on the row count in Column B. Im certain Im not putting this formula into the macro correctly, but Im new to this and any help would be greatly appreciated.

    Selection.Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
    Range("P1").Select
    ActiveCell.FormulaR1C1 = "Store Number"
    Selection.Font.Bold = True
    Range("P2").Select
    ActiveCell.FormulaR1C1 = Mid(O2, Find("-", O2) + 1, Find("^^", Substitute(O2, "-", "^^", 2)) - Find("-", O2) - 1)
    Range("P2").Select
    Selection.Copy
    Range("P2:P" & Range("B" & Rows.Count).End(3)(1).Row).Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Range("A1").Select

Thanks in advance.

Thanks,
Ray