Just down from Kirkudbright, on the west side of the bay, there's a line of rock art sites, and this is the southern end of the line, the closest to the sea. Supposedly proximity/views of the sea is an important factor with the RA in this neck of the woods.
I couldn't sea the coast from here, but it's such a tiny, 'blink-and-you-miss-it' motif, amidst oodles of likely looking outcrops, so it was tempting to think that this may just be the tip of the iceberg, and that more impressive panels would be found in the higher areas with wider views. But I did'nt get to check the other nearby stones, so I couldn't comment.
There's a sort of sheepfoldy/storage thing where it's possible to park, and the stone is flushwith the ground, so easy to miss. It's near a more conspicuous natural outcrop with a possible cup mark.