The 20-year-old made over 20 first-team appearances for parent club Dundee last term, scoring three Premiership goals in the process.
McKinnon has picked out Waddell’s aerial prowess as a valuable asset for his side and expects the 6ft 2in centre-half to dominate both his own and opposition boxes in the season ahead.
Speaking to media and communications officer Jonathan Mitchell, McKinnon said: “I’m delighted to have signed Kerr Waddell on an initial six-month loan.
“He’s a big centre half, very commanding in the air, very aggressive, and he played 20 times for the Dundee first-team and scored goals, so he’ll be a real asset at both ends of the park.
“I think it’s important to have that. I like my central defenders to be strong in the air. He’s still a young kid with a bit to learn but he has experience in the Premiership and he’ll be a good addition for us.”
Waddell was amongst the players to get game time in a closed-doors friendly against Motherwell on Tuesday, and McKinnon said it was a valuable exercise for his side.
The 47-year-old added: “We won 2-1 with goals from a trialist and Jim McAlister and it was a good workout for the players.”
Image: Jonathan Mitchell