You make the call?

[blue]

It's up to the runner to avoid interfering with the fielder making the play. The runner has to do whatever she has to do to allow the fielder to make the play. Not being there to see the actual play, I would side with the ump because it is his/her judgement.
Having said that, it sounds to me like F3 was set up for obstructing the runner on the steal, and she was saved by the ball being hit in her direction.