Obstruction on last play of inning

[Little Jimmy]

This happened today and I wondered what the mechanics would be if it was twisted slightly. Utrip tourney but I don't think it makes a difference. R1 on 2nd. R2 on 1st. 2 outs. B1 hits a gapper. As R1 rounds third she is obstructed by F5 (I signal) and she continues toward home. Then R2 to tries to stretch her advance to 3rd. She is thrown out for the 3rd out of the inning, but plate ump says runner just crossed the plate before the out, run counts. All is hunky dory.

But what if R1 didn't score before the 3rd out? She was obstructed. Simply announce the obstruction, award home, and count the out at third as the third out of the inning?

This is probably straightforward, but just wondering.