I collect Ricordia and when I get them in, sometimes, they are not attached.
The method I prefer using is netting. In fact, I went to Hobby Lobby and purchased a yard of cheap bridal netting (be careful not to get netting that is dyed); cut it in strips and attached the ricordia to the rock. There are three factors to consider. #1 you have to wrap the netting to assure it won't escape. They are pros at the escaping act during the night! lol #2 Don't wrap it too tight as they will expand once they lose their attitude; and #3 BE PATIENT...lol it takes time. Mine takes a week at least... Sometimes two.
Another method is putting them in a glass jar with loose rubble at the bottom of the jar... and set it in your tank and wait for them to attach.
Hope this helps you...and good luck!
water`bug