The number of recon accts to be defined is dependant on various factors, like how your management wants to see the reports.. whether they want to classify the cost based on CO object class or by Co types etc..
However the basic config you got to follow is:
1. Activate Recon accts (if you have created CO area newly, it would be active).
use T.code: KALA
2. Assignment of Recon document type to the Controlling area.
3. Creating clearing accts (that you want to us! e for reconciliation. During FI-Co recon.. inter company clearing accounts will be automatically credited or debited and now you need to create offset acct which will show up in P&l acct).
Acct determination set up thru T.code: OBYA
4. Maintain accts for Automatic Recon posting.
5. Assign Number ranges to Recon activity.