What you can do is to check if there is any rock stubble attached to the foot of your rics. If there is, get some super glue gel from Homefix or any hardware store. dry the rock stubble on the ric, pit 2-4 drops of super glue glue gel on the rock stubble and place the ric on the rock you want to stick the ric to. Then put the ric and rock back into your tank to cure. This is what I do for all the rics that you see on the rocks in my thread.
If there is not any rock stubble on the foot of your ric, then get a betta box, fill the bottom with coral chips and place your ric on the coral chips. Put the betta box where there is very little current. The ric should attach to one of the coral chips with a couple of days. You can then glue the coral chip the ric is attached to any rock you want.