The V-Lower set-up with a swimmer requires a rescue vest, a belay team on each side, the rescuer/swimmer, and always set downstream safety. In an emergency, the rescuer/swimmer will need to open the quick release belt and they will float downstream. Attach to an integrated tether or on a safety ring. If you are using a carabineer as your safety ring, make certain it is a locking carabineer and it is properly locked. Here is a video example of this technique: V-Lower Example.
Ideally, use a tow tether or a safety ring built for your jacket. Either option has a free-floating ring that slides smoothly along the quick release belt and is very unlikely to get caught on anything. If you have to use a carabineer instead, make it a locking carabineer and make certain it is locked and the belt slides smoothly through the carabineer. Both ropes are attached to the carabineer, ring, or tether. Both ropes are used to position the rescuer by pulling or feeding line. Avoid a vector pull scenario by setting a small angle, at most 90 °. This greatly reduces the load on the two belay teams or persons.