Kim, who arrived for £2m from Japanese club Cerezo Osaka last summer, shone in the final weeks of Cardiff's Championship winning season and Mackay said he wants more from the exciting midfielder in the Premier League including more goals.
"We wanted to add goals to the overall make-up of his game and he has done that. I think he showed some sublime little touches and he got on the score-sheet which is important too," said Mackay to the Western Mail.
"It's good for him too going into a slightly different role. He's still only young you have to remember that and he's come in from a completely different culture. There's the language too. His English has improved massively and his mother and father are over here with him too.
"I think you saw last season how he got to grips with the Championship, the type of football involved. I think we saw the improvement. I know his raw talent it was about giving him time to settle."