Loop Through Columns And Sum Them At Bottom

I've been working on coding a summary sheet that pulls data from
worksheets in the active workbook.

I'm almost done, but am stumped at writing some code that will loop
through the columns that I have copied and total them. I recorded a
macro, but nothing happened when I ran it.

What I have now is this code snippet that I found which works
perfectly when I put my cursor in the active cell.
I am not sure how I should write it into my sub.

code that I found that works:

Set rng1 = ActiveCell.End(xlDown)
Set rng2 = rng1.End(xlUp)(2, 1)
rng1(3, 1).Formula = _
"=Sum(" & Range(rng2, rng1).Address(False, False) & ")"

I tried this:

For Each col In NewSh
ColNum = ColNum + 1
Range(RwNum, ColNum).Select

Set rng1 = ActiveCell.End(xlDown)
Set rng2 = rng1.End(xlUp)(2, 1)
rng1(3, 1).Formula = _
"=Sum(" & Range(rng2, rng1).Address(False, False) & ")"

Next col