The winger featured 41 times for the Light Blues last season as they won the Third Division title by 24 points.
But with a much more experienced squad at his disposal this season, manager Ally McCoist has used McKay far less than many people expected.
The bulk of his outings since the summer have been in Gordon Durie’s under-20 side, with just 65 minutes of top-team action coming otherwise.
McKay, who turns 19 on Monday, last featured at senior level back in September, when he played the final seven minutes of a 1-0 win at Forfar.
Manager Ally McCoist spoke last month of his confidence that the teenage talent would find his best form again after struggling to stay involved in recent months.
But with no under-20 fixtures scheduled until January 21, he has taken the opportunity to farm McKay out to gain additional game time.
Morton, now managed by Dean Shiels’ father Kenny, have five games pencilled in for the duration of the Scotland under-19 cap’s stay at Cappielow.
He could make his debut tomorrow against Hamilton, with further fixtures coming against Dumbarton, Raith Rovers, Livingston and Queen of the South.
McKay is set to return to Ibrox on January 26 and he’s the third young talent to leave from Auchenhowie for a temporary stay elsewhere in the last week.
Luca Gasparotto is also spending a month a Stirling Albion while striker Calum Gallagher is at East Stirlingshire for the same period of time.
It is understood former Rangers defender Darren Cole has gone to Greenock with McKay after becoming a free agent earlier this year.
Both players will join up with another ex-Light Blues trainee, 22-year-old striker Archie Campbell.
Copyright 2014. Permission to use quotations from this article online is only granted subject to appropriate source credit and hyperlink to www.rangers.co.uk