The bust image is Charles IV of Spain, and the exergue is 1798, not 1794 as shown. It is one of my most valuable coin to date. Minted in Mexico City.
This coin used to circulate in Peninsular, especially northern state - Pattani, Perlis, Kedah, Kelantan and Penang - and known as "Rial", taken from its real name - "8 Reales". It is the official currency of the world at that time, and accepted by almost every government.
(I have spend money from my salary to pay for this, quite expensive!)