People often confuse VaikhAnasas with Sri Vaishnavas because of their similar outward resemblance.
VaikhAnasas are not formally
affiliated with the tradition of Ramanuja. They also do not follow the pAncarAtra Agama which dictate the ritual of
samASrayaNam or panca-samskAra. As their name indicates, they follow the vaikhAnasa Agama, which is a different set
of Vaishnava ritual texts. The vaikhAnasas trace their guru-paramparA to Vikhanas Muni. In fact, in the place of 'SrImate
rAmAnujAya namaH' which is characteristic of all Sri Vaishnava correspondence, they typically write 'SrImate vikhano munaye
namaH' (or some variant). Their doctrines claim origin from Atri, Bhrigu, Kasyapa, and Marici, four rishis who according
to their texts were taught directly by Vikhanas Muni, an incarnation of Vishnu. The vaikhAnasasare strictly hereditary --
one must be born (or adopted) into a vaikhAnasa family to be considered a vaikhAnasa Vaishnava.
As you are aware, the
pAncarAtric rite of panca-samskAra establishes a formal link between the initiate and an acharya of the tradition of Ramanuja.
The vaikhanasas as stated above do not have such a ritual, and do not formally have a connection with Ramanuja. However,
while they are not branded with the insignia of Vishnu, they believe that Vishnu himself comes to the womb in the third month
of pregnancy and brands the child with the sankha and cakra. This is known as 'garbha-samskAra' and is dictated once again
by the vaikhAnasa texts.
The vaikhAnasa texts are overwhelmingly concerned with the details of temple ritual and largely
do not contain philosophy. Most of the philosophical teachings are similar to the pAncarAtra, including a parallel five-fold
manifestation of Vishnu. They also have a notion of the 'nishkala' form of Vishnu -- the formless, primeval Vishnu which
is perceived only by the highest of yogis and which is beyond even Brahma -- and the 'sakala' form, which is figured, divisible,
and emanated. It is in this form that Vishnu responds to devotion and meditation. There is also 'sakala-nishkala' combination
of the two, which is found in the sAlagrAma. (These details may also exist in some pAncarAtra text)