I need to write a general VBA program that will bootstrap any given size development triangle

Question

I want to be able to bootstrap the total from any size development triangle in reserving.

Sub Boot()
Dim x As Range
For Each x In Range("B:B")
If x.Value = "" Then
x.Select
RowCount = ActiveCell.Row
MsgBox (RowCount)
Exit For
End If
Next x
End Sub

Dim i As Integer
Dim j As Integer

For i = 1 To RowCount
For j = 2 To RowCount
If i = 1 Then
Selection.Cells(RowCount + 2, 1).Value = "Cij"
Selection.Cells(RowCount + 2, j).Value = Selection.Cells(1, j)
Selection.Cells(RowCount * 2 + 3, 1).Value = "IDF"
Selection.Cells(RowCount * 2 + 4, 1).Value = "CDF"
Selection.Cells(RowCount * 2 + 5, 1).Value = "% Dev"
Selection.Cells(RowCount * 2 + 7, 1).Value = "D'ij"
Selection.Cells(RowCount * 2 + 7, j).Value = Selection.Cells(1, j)
Selection.Cells(RowCount * 3 + 9, 1).Value = "C'ij"
Selection.Cells(RowCount * 3 + 9, j).Value = Selection.Cells(1, j)
Selection.Cells(RowCount * 4 + 11, 1).Value = "Rij"
Selection.Cells(RowCount * 4 + 11, j).Value = Selection.Cells(1, j)
Selection.Cells(RowCount * 5 + 13, 1).Value = "R*ij"
Selection.Cells(RowCount * 5 + 13, j).Value = SelectionCells(1, j)
Selection.Cells(RowCount * 6 + 15, 1).Value = "C*ij"
Selection.Cells(RowCount * 6 + 15, j).Value = Selection.Cells(1, j)
Selection.Cells(RowCount * 7 + 17, 1).Value = "D*ij"
Selection.Cells(RowCount * 7 + 17, j).Value = SelectionCells(1, j)
Selection.Cells(RowCount * 7 + 19, 1).Value = "IDFs"
Selection.Cells(RowCount * 7 + 20, 1).Value = "CDFs"

Else
Selection.Cells(i + RowCount + 1, 1).Value = Selection.Cells(i, 1)
Selection.Cells(i + RowCount + 1, j).FormulaR1C1 = " = If(IsBlank(R[" & -      (RowCount + 1) & "]C1)),"""",(Sum(R[" & -(RowCount + 1) & "]C1)):RC[-1]"

That is how I've gone about starting it but am struggling to get the required formulas in the right format. Any help would be appreciated