How to install an earthing system?
Here in El NEC country, we like to see 2 grounding rods at least 2.5m long. They should be at least 2m apart, but the farther the better, ideally opposite corners of the building.  Their job is to protect you from voltage gradients caused by lightning.  

Those grounding rods are connected to the grounding/earthing bus, which is kept separate from the neutral bus.  

In addition, we tie neutral to earth at exactly one place: the first point past the electric meter/service beginning.  Beyond that point, neutral and earth/ground are kept rigidly separate and never connected.  That means for instance, if we have a subpanel (a second panel fed by the first), we run separate neutral and earth/ground wires and keep separate neutral and earth bus bars also.  

This separation is especially important downstream of an RCD/GFCI.

It isn't our thing to put an RCD on an entire board or facility, that's Europe's thing.  We put RCDs on individual branches, and they are sensitive 6 ma RCDs which assure trip before a person can possibly be injured.  You probably can't use one that sensitive on an entire panelboard, you will get a lot of nuisance trips if you try.  The European method uses a 30ma RCD.