A couple of things:
First: - this program is for regular force NCMs only, not Reserves or civilians. In order to qualify you would need to serve in the ranks as an NCM for approx four years, and the program is EXTREMELY competitive, depending on desired Officer occupation (e.g. three spots for Pilot, five for AERE, etc).
Second:
Since you already have cadet experience, stick with that. You say that you intend to apply to RMC, which means that you are going to apply to become a leader in the CF. This means that you will need to demonstrate leadership experience to be a competitive applicant. Look at the qualities of a good Officer, and think of ways that you can demonstrate those traits in yourself. For example - good grades demonstrate intellect, seniority in cadets can show leadership ability, responsibility, and a desire for the CF way of life. Community involvement gives the CF an idea of your moral alignment. In the end, the Reserves can give you a bit of a leg up in the event you are selected, but you have to be selected first.