I have made a simple adapter for a little bottler to allow use on bigger taps...
Get a normal pre drilled rubber demijohn bung from your home brew shop. Drill half way through with a drill slightly smaller than your tap so it's a tight push on fit. Then push the little bottler into the hole (originally for airlock) in the other end...
It will allow widely different sizes more so than can be achieved with the little connecting tube supplied.