Mackie has scored just once in 12 appearances since his move from Queens Park Rangers in the summer, but the Scotland international believes that he is not far away from contributing to his club's goal tally on a regular basis.
The 28-year-old told the Nottingham Post: "I have played in a few different positions, but I have settled in now and I missed games in pre-season and although I am a fit lad, it does take time to get into your full stride.
"I feel that I've got that now and I'm sure that the goals will come. I just need a couple of goals and I'm very confident in my ability to get on a run and do well. I scored fairly early in my Forest career and I wanted to go on a run, but that hasn't really happened.
"It has been fairly frustrating. I've missed good chances, but I'll keep putting myself there and luckily we are in touching distance and doing well."
Mackie could be selected in the starting lineup to play Bournemouth on Saturday afternoon.