The 18-year-old winger is considered a prodigious talent at Rangers and he spent the first half of the season on loan at Scottish Championship side Inverness.
He made eight appearances for the club in the league before he returned to Rangers and was loaned out to Raith Rovers for the second half of the campaign.
Robertson is a big fan of the young winger but insisted that Kennedy is a still a very young player and he will have to get through in dips in form, which will be natural given where he is during his career.
The Inverness coach insisted that the only thing the winger needs to learn to become a top-class footballer in the future is how to become more consistent and perform at a certain level week-in-week-out.
“He’s a prodigious talent but he’s still a puppy”, Robertson told The Athletic.
“There are times he will be on fire and others when he will dip.
“It’s a consistency thing for Kai right now, as the tools are there to be a top-class footballer.”
Rangers will want to see Kennedy continue his development at Raith Rovers before he returns to Ibrox at the end of the season.