We are aware, and thanks for the community bringing this to our attention.
Whilst we cannot go into the ins and outs of our legal work as we don't want dodgy sites and individuals to know the specifics of what we're doing, we can assure you that the Player Support Anti-Cheating Team and our legal department are actively working to stop sites such as this, and have been for some time. Please also report to Facebook, as we have no direct control over what is posted on a 3rd party site.
Please remember to keep an eye out for the blue tick on Facebook for any RS or OSRS ads.
Thanks for raising awareness! Together we can reduce the amount of players who fall victim to phishing ads like this.