Did I make the Right Call!

[Steve M]

DW,
See what StuCarey said. He's right - try it.
I have rewritten your post, saying what I think you meant to say.

No runners on, no outs. Batter hit a pop up halfway from home to first base.
F3 is running in to catch the ball. F1 is running to foul line to catch the ball.
BR is running to firstbase. (you can see where this is going) BR moves to the right in foul ground to miss F3. F1 follows the ball into the BR in foul ground.
I called foulball because in my judgement the runner was trying to miss everyone and the ball was moving F1 into the BR. So did I make the right call?

And by the way the defense’s coach went wild on my call saying “that was interference on the BR."

The question to be answered is what fielder should have fielded this ball? That fielder is protected, no other fielder is. If F1 - the pitcher - is the player who you felt should have fielded that ball, your call should have been "dead ball, that's interference, out."