Welcome to TreasureNet !!
Great looking coin. Felipe III, 1616 Assayer 'F'. Appears to be the size of an 8-reales piece and should weigh about 27+ grams. No 4Rs, 1Rs or 1/2Rs were made in Mexico in that year--other than a 2R; and your coin appears larger than a 2R. That design is rare; it's a keeper !!
Don.........
My concern now: Is your coin the exact same one as this 8 Reales (1616 - 1617), Portal Fuenterrebollo
or...is is a repo of this referenced coin or... is it not the same coin but nearly identical.
Don.....
Steps: First, need to determine if it's authentic or a repo.
Second, determination it's metallic composition if not real; third, its value.
You may wish to send the coin to Sedwick for authentication: FAKE COBS: ALERTS AND DATABASE by Daniel Frank Sedwick, LLC.. He's one of the good guys.
Don........