This is what my Merriam-Webster's 11th Collegiate Dictionary says about "rimming":
rim
Function: verb
Inflected Form:rimmed ; rimming
Date:1621
transitive verb
1 : to run around the rim of <putts that rim the cup>
2 : to serve as a rim for : BORDER <cliffs rimming the camp>
intransitive verb : to form or show a rim