[5] Jaer's performances at the 2013 Craven Week led to his inclusion in the South African Schools side and he made one appearance for them in a 17–13 victory against France in George in August 2013.
[15] Jaer scored a try in their subsequent promotion play-off match against Eastern Cape rivals Border U21, helping them to a 64–9 victory[16] and a place in Group A of the competition in 2015.
In March 2015, Jaer was named in an extended South Africa Under-20 training group as part of their preparation for the 2015 World Rugby Under 20 Championship.
[17] While he didn't feature in a friendly match against a Varsity Cup Dream Team in April 2015,[18] he was included in the squad that toured Argentina in May 2015.
In December 2015, Jaer was one of the first twenty players that signed contracts to play for the Southern Kings in the 2016 Super Rugby season.