How?

[Flyrodde]

If I didn't know the water, I would fish a hopper with a hare's ear or PT and brassie dropper. I would fish upstream working from the inside edge to the undercut. Working every lane before lengthening my cast and doing the same thing again. OR I would dead drift a white streamer with a rust colored stone fly above it along the undercut and swing it into the inside bank working downstream taking a step after every other cast or so.

PS

There was probably a fish right where the person is standing.