Tabraiz Shamsi was not picked up in the IPL auction in February but has been signed as a replacement player by Rajasthan Royals.
Shamsi, 31, represents The Titans in South Africa's domestic cricket, and made his international debut for the Proteas in 2017.
South Africa beat West Indies by one run to take a 2-1 lead in the T20 series courtesy of Quinton de Kock's 72 and Tabraiz Shamsi's economical spell.