The 25-year-old second-row arrives in Barnet following a spell in the United States with the Dallas Jackals.
Mcfarland, who is 6ft 6 tall and weighs 115kg, won both of his caps as a replacement against Tonga.
Prior to playing in Major League Rugby, McFarland played for the Savai’i Vikings in the Super Nine Rugby competition in 2018 and 2019.
During that time he also represented Samoa at basketball in multiple international competitions.