Visited 12th October 2002: It's taken me ages to post this because I've been trying figure out whether Banc Rhosgoch Fach is the remains of a burial chamber or a stone row. I'm still not sure, but if I had to put money on it I'd go for the former. This is based on all the records I've viewed at the NMRW. Apparently Burl's Carnac to Callanish stone row book describes it as a stone row, but I have no idea where the evidence for this comes from.
There's not much left to look at on the ground at Banc Rhosgoch Fach. There are two remaining stones, both looking like they've been dumped at some stage. They lie just north of a footpath, but they're surrounded by crops, so not necessarily accessible.
We approached from the north east (starting at SN435545), and from early on in the walk you realise that the farmer isn't keen to encourage walkers. The footpath isn't marked, so you need a map. We passed through quite a few dilapidated gates (I think it was four), two of which were bound shut with barbed wire! The trickiest part was deciding which side of the boundary to walk on to get to the stones (you just can't tell where the footpath goes). We struck lucky by staying to the north of the fence.
Only worth a visit if you're pretty keen (and not pregnant).