Hi guys,

I would like to know if is possible to limit the coverage area of the Mikrotik RBMETAL2SHPN? I want to install several antennas outdoor but I don't want them to cover more than 300 meters each, is it possible? If so, how?
Thanks!!

There is nothing like 300m radius. The distance depends on both sides of the link and local conditions. You can always use lower gain antenna and set lower tx power according to your needs.

You can also modify the tx power, this can help you the coverage is less and also with less noise.

and the only way to know how much tx power to use is trying it, right? or there is some kind of TX/Coverage table I can use as reference?

If you do not know what is the other side, you cannot even guess. Just try and see. If you know the other side you can use some wifi calculator anywhere on the Web.