The one sentence to say at the counter

Most review programs die in the handoff. The owner is enthusiastic, the staff are busy, and asking feels like begging. So the sign goes up and nobody mentions it.

"Mind scanning this? It writes the review for you, takes twenty seconds."

That line works because it does three things at once: it asks, it removes the effort, and it puts a bound on the time. Nobody has to explain what the QR does or why reviews matter.

Timing

Say it while the payment is processing. The customer is standing still, facing you, with a phone already in their hand. After the receipt prints, they are leaving.

What not to add

If someone declines, drop it. The scan rate you want is about half the counter, not all of it.