A product of the Leinster Academy, Irish-born McFarland qualifies for Scotland through his grandfather from Glasgow and represented Scotland 7s previously at the 2014 Grand Prix Series in Manchester.
McFarland went to Clongowes Wood College whose notable alumni include Irish rugby greats Gordon D'Arcy, Fergus McFadden and the Kearney brothers.
McFarand has represented Ireland at all age grade levels up to and including U20s and won the All Ireland League with his club Clontarf in 2015.
In his time in Scotland previously, the winger trained with Edinburgh Rugby and played for both Boroughmuir and Watsonians in the BT Premiership. He returns to Scotland having spent a pre-season with Munster.