I know it's the old topic but I have the clear answer from the RMS admin so maybe someday, if someone decide to check this topic, will see this:
That includes any item, points, credits or any advantage you offer to players in exchange for them to review your server.
You also CANNOT promise any server wide incentive, advantage, item/point/credit give away or events when certain goals (such as getting ranked in the top x or getting x number of reviews) related to your listing.
Basically you can ask your players to make a review, and you should NOT provide any incentive for them to do so. You can say your server will get more players when other people looking for server sees their reviews and so it will benefit the server that way. "