Killing the Play

[jmkupka]

I'm in A position.
Batter swings, chops the ball straight down, bounces back up and is fielded by F2. PU points fair. I have a straight line view down the baseline & see clearly that ball is touched an inch or two foul.
Have always been told to kill a play if I see something to kill it, but is this considered overruling my partner who obviously has fair/foul responsibility?
To be fair, in that split second, there was no chance of him getting in position of 1B line extended to see the foul ball.