interfence or obstruction

[MJT]

NF rules.

Play tonight in our JV game. 1-2 count and the batter swings and misses on a ball that short hops the catcher. The ball bounces away from the catcher and just in front of home plate. The right handed batter goes to run to first base and they get tangled up as the catcher comes out to field the ball. Eventually they get untangled and the catcher fields the ball and throws her out at first base. I was the base ump, and the plate ump didn't call anything, so we had an out first at first base.

We looked in the book on the way home and it seemed to fit the definitions of interference and obstruction. What should the call have been, and PLEASE give a rule or case number.