Original photo was put up as a possible cup mark at the hillfort site and Rockart contacted me to add to BRAC, so it looks like the real deal.
The main image shows the cup marked rock. There is one deep cup at the top and other possible cup marks below. The rock itself is only partially exposed so there could be others marks. It appears to be gritstone type rock.
Access is easy, parking near Sea Houses Farm south of Craster then a short walk down access road to the sea side path. Go south down this till you come to a style and then cut back on yourself to the left and up the path to the top of Rumbling Kern.
You can clearly see the path I mention going diagonally up from left to right on Google Earth. The path cuts through gorse (darker green in the photo view on google earth) at the grid ref given and the panel is visible (on the ground not on Google earth) at the left hand edge of the gorse patch on
the right hand side, right next to the path.
You can combine a visit here with a trip to both Howick Settlement and Hillfort - image showing round trip path added to help.