RA Key in Maintenance Order

Dear Expert,

We have maintenance order settle to asset. Material and service are posting to maintenance order as P/L-cost element. In case, in the end of period, maintenance order work on process, then no settlement will be executed.

My client want the cost should be capitalized to BS account.

I think the requirement could be provide by RA key in PM order.

But, what is the process of flow? what is the tcode to execute RA Key? Should be calculate first, or just execute then settle?

What is the disadvantage/advantage using RA Key?

Thanks in advance,

Dewi