The last time I updated the PDGA vs. River City Ratings analysis I've done (admittedly several months ago), the River City Ratings were, on average, 1.019x folks' PDGA ratings (adjusted to scale). So, again on average, a 1000-rated PDGA player would have a River City Rating of 10.19.
Overall, for the folks who had both PDGA ratings and River City Ratings, as of the last time I updated the comparison, the correlation between the two (r squared) was 72.79%.
aka 'teddy ballgame'
2012 RCF Bag Tag #411
2012 SICG Bag Tag #30