How to report a link scheme to google?

I know 5 reciprocally linked websites (all of them are made by 1 owner) with low quality and very thin content, without any other do-follow backlinks, but ranking incredibly high (half of them is on the 1st position at non competitive market).
Of course, my business is highly affected by this.

How would you proceed to report them to google?
At the end of this support.google com /webmasters/answer/66356?hl=en there is "If you see a site that is participating in link schemes intended to manipulate PageRank, let us know"...
but that link is to report paid links not link schemes....

Does anybody have experience with reporting to google by this way? Would you expect they take a manual look on this case and if they see something is going against rules they take a quick action?

If you can't beat them, join them. Why not do the same and rank yourself higher?

"I know 5 reciprocally linked websites (all of them are made by 1 owner) with low quality and very thin content, without any other do-follow backlinks"

Doesn't sound like enough to make it rank very highly unless those five sites have a lot of power in them?

How about ranking your business website (or websites) above them? Go with this mate.

If you can't beat them in SERPs, then why you are trying to harm their game?