The Glasgow and Ayr centre has joined the Scots on a loan deal.
Academy scrum-half George Horne (Glasgow Warriors & Glasgow Hawks) could also make his debut from the bench.
Robbie and George are two of four young players to join London Scottish on loan for the next part of the Championship season.
Second row Andrew Davidson (Glasgow Warriors & Glasgow Hawks) and prop Jack Cosgrove (Edinburgh) have also been training with Scottish.
London Scottish Club President Rod Lynch said: "I am very pleased to have these players join us from Scotland. Now the World Cup is over the Scottish clubs are gearing up for the remainder of the season and we are delighted to be in a position where we can co-operate in the development of these young players."