It makes it so you can start getting RO from a planet, if the planet produces RO. If the planet does not produce RO, you won't find any. A trader starts with a 10%, and with each rank gains +10. So a rank 9 in AMC the trader will get 100% of the ore the planet produces. Others can not extract any RO, and must have AMC to acquire it from the planet. They get 3% per rank to a max of 27%.
If you trade with a planet that has RO, you can gain RO that way. As you can see the most effective way to gather RO is trade with a trader.
If the planet produces RO, it can mine RO with the skill. Some planets just don't produce RO. I will bring up the description with the team and see about changing it.