Switchitter: An RBI is awarded on an error only if, in the scorer's judgement, the run would have scored on that play anyway. If the run would not have scored without the error, the hitter does not get an RBI. Examples:
-No outs or one out, runner on third and outfielder drops what would otherwise be a sacrifice fly. The hitter gets an RBI, is NOT charged with an at-bat, gets credit for a sac fly, and reaches first on the error. The run from third base is earned (depending on how he got there); if the hitter eventually scores, his run is unearned.
-No outs or one out, runner on third, corners in, middle infielders back and 2B boots groundball. If scorer feels the runner would have scored anyway because 2B was playing back, the hitter gets RBI, but IS charged with an at-bat and reaches on an error. Run from third base is earned. Hitter on first base would be unearned if he later scores. (If the same thing happened except the groundball was to the 3B playing in, scorer might rule no RBI because the runner may not have scored without the error. Scorer's judgement.)
-Suicide squeeze bunt. Runner scores from third and fielder throws the ball away so hitter is safe at first. Scorer determines that the bunt was good enough to score the run regardless of what happened to the throw at first base. Hitter gets RBI, is not charged with an AB, gets credit for a sacrifice, and reaches on error.