This formation is actually one of the examples in the CCA mechanics manual on page 73. Technically the shirt wing has the back receiver, the deep wing has the outside receiver, and the B has the “point” man and inside receiver.
That being said, the back receiver doesn’t really need to be keyed. He can’t foul or be fouled before one of his teammates. And most of the time, the other two guys off the line aren’t a threat either. So really, we just need to see the point man at the snap and then it’s straight to zone. Let them declare where they’re going and then I should be obvious who has whom. The B will take inside, the deep wing will take whoever goes vertical, and you take the one who stays close. The biggest thing is if you see this on film, pregame it with your crew. Make sure everybody is on the same page with how you’re going to treat it.