Not quite sure what do you mean about rotating add, but the forum ads has been suspended a while ago, so your next choice is conducting a bounty campaign (since it's altcoins). But bounties marketing aren't work these days due to poor quality, you're better to launch a signature campaign with Bitcoin payment so you could have a chance to get higher quality members especially the payout is higher than the rest campaign and long term purpose.

You can contact a campaign manager on this thread [LIST.] Campaign Management Services