Dear Kins,
It depends what is the purpose of Residual stress (RS) consideration. If you want to get the precise stress profile, then you must have the exact profile (distribution) of the RS and add to (For tensile RS) or substract it (for compressive RS) from the applied stress on your component and then include the resultant into your finite element model as a new applied stress (load) condition. The problem is that always finding the absolute value (or distribution) of the RS is not an easy task, but if you have it then there is no problem to do as I explained.
Regards
Afshin