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Ismeal Kabia was brought down in the box by Emmanuel Fernandez in the first half, but referee Don Robertson waved play on.
Speaking on the VAR Review Show, Collum explained that there should have been a longer VAR check, with a spot-kick expected to be awarded to the visitors.
"It should have been a longer check, without a doubt. For us this is a penalty kick without question," Collum said.
"There will be occasions where attackers in the penalty area will play the ball, and there will be inevitable light contact, softer contact. Here, it's quite clear for us that this is reckless contact.
"This would probably fall into the category of reckless, so a yellow card would be expected here for that kind of stepping action on to the foot.
"It's simple to say the decision is wrong and we would agree with that.
"We had a discussion with the Premiership managers only the day after this match and they agreed completely that they would expect a penalty kick for that."
Rangers won the game 1-0, thanks to Bojan Miovski's 91st-minute strike.