When you attach the line to your rescue vest, your first choice is a tether, then a continuous ring designed for that jacket, and finally a locking carabineer.  Don't use a non-locking carabineer since the gate may open and snag on your PFD and hinder the belt release.  Set a strong belay position and add a second person to assist the belayer by pressing down on them.  They will need to pull in two persons instead of the usual one.  Someone else can assist by grabbing the taught line and moving their grip down the line in a vector pull.  This lightens the load for the belay person and brings the rescuer and swimmer to shore much faster.  It always helps to have extra landing zone help.  This technique is often used for rescuing and unconscious swimmer.  Unconscious swimmers may have a C-Spine injury.  These types of injuries require multiple persons to immobilize the head and safely evacuate.  Here is a video example of a live-bait rescue: Live Bait Rescue.