The OG questions should be more than enough for RC . Don't try to just get the answer right , try to learn something from each problem . Do the 2 OGs and the gmat prep question pack 1 , that should suffice . Two important points - review ALL OG questions even if you get the answer right . Secondly make sure that your practice sessions are timed ! This is VERY IMPORTANT .
If you really want some more RC questions , you could try doing the E-GMAT
course . But I strongly believe that the OGs are more than enough .
Hope this help ! Good luck ! Post back if you have more questions ! Posted from GMAT ToolKit