RA Key with No result analysis

Hi Experts

Probably a very basic question.

If I have a customer T&M Project where I want to recognize revenue as its incurred and recognize cost as its incurred, Do I really need a result analysis in this case?

I would need to settle cost & revenue to profitability segment though.

So can I leave the RA key blank in the WBS or assign some RA key which does not make any calculation. For the later, what would be the configuration? Choose any method and just to not create any line ID assignment in OKG4 ?

I am looking for create a RA Key which is for " No result analysis", Just to make the business process even with other projects which might have a proper RA Key.

Thanks,

Krishna