It is differentiated by Yellow for RON 95and Green for RON 97 and Black for Diesel for all petrol stations. You don't need to look for the small little sign. If you have been cheated by being charged RON 97 price on a YELLOW RON 95 pump, then you can submit the picture for your complain. Otherwise I would most likely guess that you did not notice the distinctively different yellow and green pumps.