Samāśrayaṇam (meaning: resorting one’s self to an ācārya) is the initiation rite into the Śrī Vaiṣṇava Sampradāyam. It’s conducted for all those who seek to be full fledged members of the Śrī Vaiṣṇava Sampradāyam. Here is a thread of an old film adaptation showing this rite:

The first saṃskāram that is administered is known as Thāpam. The ācārya stamps with heated emblems Viṣṇu’s Sudarśana Chakram & Pañchajanyam (conch) on the respective shoulders of the person undergoing Samāśrayaṇam. Hymns to Sudarśana & Pañchajanya are chanted while doing so.

The second saṃskāram that is administered is known as the Ūrdhvapuṇḍram. Here, the Thiruman, representing Nārāyaṇa's Lotus foot, and the Śrī Choornum, representing Mahālakṣmī, are applied in different parts of the body while chanting certain nāmam-s of Nārāyaṇa.

The third saṃskāram that is administered to all is known as Nāmam. The ācārya renames the person undergoing Samāśrayaṇam with the suffix Dāsan or Dāsī. This is to destroy ahaṅkāram (ego/pride) & mamakāram (selfishness) & to commit oneself to serving Nārāyaṇa & Rāmānujācārya.

The fourth saṃskāram that is administered is the Māntra Upadeśam. Here, the ācārya reveals the all-powerful Thirumantram (Aṣṭākṣarī), Dvaya Mantram, & Charama Ślokam to the person undergoing Samāśrayaṇam. Any person receiving this upadeśam is expected to chant them daily.

Finally, the fifth saṃskāram is known as the Yāga Saṃskāram. Here the newly inducted disciples of an ācārya & Śrī Vaiṣṇava-s learn the proper methods of worshipping Śrīman Nārāyaṇa. Samāśrayaṇam is also known as the Pañca Saṃskāram because of these five rites.

Note: This is a general layout for Samāśrayaṇam. There are slight differences that exist in how each of these saṃskāram-s are conducted (based on one’s chosen ācārya). Nonetheless, the ultimate goal of transforming an individual to a full fledged Śrī Vaiṣṇava is the same.

Samāśrayaṇam is truly for everyone and anyone that wants to become a Śrī Vaiṣṇava. Rāmanujācarya even conducted it for a socially ocstarized Caṇḍāla woman to bring her into the Śrī Vaiṣṇava Sampradāyam and give her a respectable role in the temples of Thirunagari. https://twitter.com/vishnudasa_/status/1347646469566816260