The method I use is to put the rics on a coarse substrate (like crushed coral) and control flow so that they aren't getting blown around. A small floating box that you can somehow hold to the edge of the tank (to keep it from floating around the tank and flipping over). They will usually attach to the crushed coral in less than a week.
Knop did an article on rics in the most recent Coral Magazine that I thought was interesting. They frag themselves naturally this way, but I hadn't thought of intentionally trying it. Once they are attached to the crushed coral, they will likey be attached to a couple of pieces of crushed coral. Glue the 'now-attached-to-crushed-coral' ric to a new rock, allowing one piece of crushed coral to hang over the edge of the rock. This will slowly pull the ric in half, giving you two where you had one, with a natural propagation method. I'd make sure it is healthy before stretch propping it (or propagating anything, in general).