The talented back has an impressive pedigree - he has played for New Zealand Schools and New Zealand Colts.
He was signed for the Highlanders for the 2018 season and played two games with just the one start, against the Reds in Brisbane in late May.
McKay (21) is a player of undoubted promise and has plenty of pace.
He plays for Canterbury in the Mitre 10 Cup and has played more than 30 games for the province.
McKay played at first five-eighth earlier in his career and played in that position for the New Zealand Schools team in 2015.
With the Highlanders looking round for another first five-eighth for the campaign next year, McKay could be a candidate to play there but the Highlanders are not looking at pursuing that option.
The Highlanders see McKay as an outside back with potential to play fullback or wing. He has played on the wing for Canterbury in its opening round of the Mitre 10 Cup.
It is a wise move by the franchise to sign McKay as he has potential and could fill the shoes left by Ben Smith when the Highlanders veteran moves on.