Here is what I am trying with one of my ricordea florida. I am not sure about this method, but perhaps you can try it. I took a small tupperware container, put a little sand in the bottom, then covered that with a layer of live rock rubble, then put the riccordea in the container on top of the rubble. My plan is to let it attach itself naturally to rubble in the container, then attach that rubble to a larger rock.
Oh, I also put a piece of mesh over the top of the container to keep the ric from blowing out, and to keep hermits from getting in there.