the last obstruction post ever(just kidding)

[tcblue13]

I would like for someone on the forum to detail the mechanics of an obstruction call.

Sitch: R1 on 1B, B3 hits line drive to LF, moving in to cover 2B F4 obstructs R1 just before she rounds 2B not a crash but some contact is made. F7 pegs the throw to F5 for the out on R1 at 3B. F5 then throws to F4 and the BR is tagged out at 2B.

At what point in the play is obstruction called? Is the play killed as soon as the tag is made at third or does the delayed dead ball signal (which I assume is given at the monent of obstruction) allow the play to conclude with the play at second?

If someone would walk through this play and break it down at each point when the Ump takes action, that would be helpful to me.