Very good question.
First of all, you must really help out your PSAs which should really tempt them to comment and rate you.
Rather than this what else? you may ask your PSAs to rate you every month by sending them a team mail. But asking them to rate you every month, will annoy them.
so do your work by helping your PSAs , then SFI will remind them to rate you.
Definitely they will rate you then.
Hope i helped you