if you hav never used a rotary buffer before i wouldnt practise on your new paintjob

@Mochhi, the reason why Aarronng asked if it was done profeesionally or not was the gauge the amount of work required or maybe even to suggest her go back to the guy who did the job to get the cut back done

any compound will do, you need a pretty fair abrasive then will need to go through subsequent stages with a finer polish to remove any marring from the original cut back