This vigraha is of a Vaishnavite saint, as identified by the vertical religious mark on his forehead and the Tri Dandam.
Everything you see in a Ramanuja vigraha is here: hands in Anjali Mudra, sitting in Ardhapadmasana, shaven head and rear tuft. There are two differences. Tri Dandam, is on his left side and he is not wearing any sacred thread. The photos below compare Ramanuja and this Saint. For more information on Ramanuja please see the blog on Ramanuja Acharya.
As is the case with most of the Vigrahas the Saint is sitting on an inverted lotus (Padmapeetha) which in turn is supported by a Bhadrapeetha.
This Vigraha is about 6.5 cm in height. This Vigraha shows signs of worship, note the wear on his right foot and may be dated to the nineteenth century.
It is most likely from Karnataka, as some of the iconographic features like side tassels of the lower garment and the runners along the shoulders (epaulet ?) are commonly seen in Vigrahas from North Deccan area of Karnataka/Maharashtra.