The earthen bank that defines it has settled to not much more than knee height, and the ditch outside it has silted and softened over the centuries, yet the geometry is remarkably intact: just over twenty-six metres across in both directions, almost perfectly round, with two deliberate gaps in the bank, each fitted with a causeway across the fosse.

This is a rath, the most common type of early medieval settlement in Ireland. Raths were typically the enclosed farmsteads of farming families, built roughly between the sixth and tenth centuries, defined by one or more earthen banks, a fosse (a surrounding ditch, usually dug to provide the material for the bank), and one or more entrances. The example at Kilkinnikin is modest in scale but structurally clear: the bank survives to around 0.7 metres in height, the fosse to about 0.6 metres in depth, and the two entrance gaps, to the south-east and south-west, are distinct enough to measure, at 1.2 metres and 2 metres wide respectively. The interior ground is noticeably higher in the southern quadrant, which may reflect natural slope or accumulated occupation deposits. More intriguingly, there is a possible souterrain associated with the site. A souterrain is an underground stone-lined passage or chamber, typically used in the early medieval period for storage or as a place of refuge, and their presence within or near a rath is a common though not universal feature.

The site sits in scrub vegetation, which both obscures and preserves it. The enclosing bank is easier to read from within the interior than from outside, where the scrub can absorb the low relief entirely.