Kalinic scored from the penalty spot to cap a 5-2 victory over Peterborough in the Carling Cup as Blackburn shrugged off concerns about swine flu to book their place in the quarter finals.
It was the Croatian forward's first strike for the club since joining from Hadjuk Split in the summer and came just minutes after he had set up a goal for Benni McCarthy. McDonald admitted that it had taken time for Kalinic to get to grips with the demands of the English game, but said that his performance against Peterborough gave a clear indication that he was finding his feet.
"It shows that he has got vision," said McDonald. "He has created a couple of good chances as well and to get that first goal will take the pressure off him of course, but that's against Peterborough.
"It takes time for a foreigner to come into our English game and adjust to the pace, to the style of play and the physical and mental demands.
"He has been patient and we have seen glimpses of what he can do certainly. He'll only get stronger I'm sure."