How can I make my formula refer to a value in a table column?

[Azuki]

I have this formula in one of my table columns.

ActiveCell.FormulaR1C1 = "=SUM(R4C" & colNoOfFAIShare & ":R5C" & colNoOfFAIShare & ")"

I want R4 and R5 to be dynamic.

4 and 5 are values derived from another table columns.

4 is actually: Delta_Ppln_Proj_raw[[#This Row],[Start row]].value

and 5 is actually: Delta_Ppln_Proj_raw[[#This Row],[No of freq]].value

How can I incorporate into the formula?

Thanks!