Plate Obstruction Mechanics

[Dukat]

I had a play last night in a FED game that reminded me a lot of the play that happened at the CWS last year where the plate umpire had the bang bang obstruction play. B1 rounds third and ball is coming in from left field. Catcher is blocking the plate and almost simultaneously R1 stutter steps, and drops for the slide as ball comes in for the apparent out (apparent for anyone that does not know the rules that is) I have no doubt I got the call right but I am not so sure I sold it correctly. Since it happened all at the same time I basically just threw up 1 arm and loudly stated "Safe Obstruction" Was this the proper mechanic for this?