OS map, Hamish Haswell-Smith and Canmore all give the location of the chapel as a pile of stones to the SW of Cara house. However, the photograph in Canmore is quite clearly of this building by the house. Also Old Statistical Account (1793) description (quoted by Haswell-Smith) describes lancet-shaped windows with splayed inshots in the east ends of the side walls, which this building has....
The chapel was also latterly used as a kitchen for Cara house and the pile of stones on the OS map is rather far to be convenient for the house. Also, although the pin on the Canmore map points to the OS "chapel", the 10 digit OS grid given by Canmore points to this building.
The corner of the sheep pen marked on the O map as the chapel.
Haswell-Smith himself says that the the OS "chapel" could easily be mistaken for a sheep pen. I think the stone structure to the SW of Cara House was a sheep pen. It measures some 30 yards by 4.5 yards and according to the OSA the chapel measured some 9yards by 6yards which are the measurements of the building on the NE side of the house. So based on the description of the Old Statistical Account of Scotland, the building close to the NE of the house was the chapel.