McKee’s first half hat-trick, an Alex Lowry penalty and a header from Kyle McClelland had the young Gers 5-0 ahead at half time before McKee got his fourth and McCausland added the 7th in the second half.
Rangers started brightly as Kane Ritchie-Hosler found space in the box to get a shot away but his effort was turned behind for a corner after four minutes.
Alex Lowry swung in the set-piece which was headed back across goal by Kyle McClelland before McKee found the net with his shot.
Midway through the first half, Rangers were denied a second by the woodwork as Robbie Fraser made ground down the left to cut the ball back to Alex Lowry who found Aaron Lyall, but the 15-year-old’s shot hit the post before being cleared by Motherwell.
However, the second goal did come just a minute later as Alex Lowry flicked the ball back to Kane Ritchie-Hosler who played in Chris McKee with the striker beating the keeper with a strong right-footed shot from inside the box.
McKee had his hat-trick on the 33rd minute as he glanced a header home from an Alex Lowry corner.
The Rangers forward was continuing to cause problems for Motherwell and on the 35th minute was taken down in the box with the referee pointing to the spot. Alex Lowry stepped up to the spot to calmly slot passed the keeper for the fourth of the game.
McKee almost had another on the 41st minute as he was played in by Aaron Lyall but his shot was touched behind by the Motherwell keeper.
From the resulting corner, Rangers did add a fifth before the break as Alex Lowry again provided the assist with the delivery which was headed into the net by Kyle McClelland.
David McCallum’s side continued to pressure in the second-half with McKee seeing his shot blocked by the feet of the keeper on the 55th minute.
Motherwell had a couple of chances midway through the second-half as they looked to get on the scoresheet but an effort from their forward was cleared well by Harris O’Connor before another chance hit the top of the crossbar before being cleared.
McKee got his fourth of the game as he tapped in at the back post from a Matt Yates cross.
Rangers rounded of the scoring for the evening adding a seventh with four minutes remaining at Matt Yates shot was parried away by the keeper by Ross McCausland was on hand to fire home the rebound.
Rangers: Hogarth, O’Connor, Fraser, Balde, MacKinnon, McClelland, Lyall, Millar, McKee, Lowry, Ritchie-Hosler. Subs: Thackray, Muir, Henderson, Devine, Hampl, McCausland, Yates.