Hi, Don't think there is any stone circle there ;), its not mentioned anywhere. I took a photo of a stone at Llanrhian, its of disputed antiquity, and I would probably agree with that, its on the triangle of road at Llanrhian....
The only stone circle is the one under the Presceli mountain Carn Meni...
http://www.themodernantiquarian.com/site/5508/llanrhian.html