depend on your particular Geico Insurance Policy and whether or not it provides you with rental car coverage -- and, if it does, to what extent you may be covered.
Damage waivers are optional; I contacted a customer service representative from Hertz, who confirmed that while you are under no obligation to purchase any optional insurance coverages from Hertz, it is up to you to determine if you have coverage for the rental car through Geico ... specifically:
-- in Puerto Rico (Some insurance providers don't provide coverage outside the US)
-- is coverage provided for Third Party Liability only?
-- Do you have coverage for both Liability & Damage?
-- What about if the rental car is stolen?
-- Does Geico only cover certain types or sizes of rental vehicles?
-- If you have coverage, is there a time limit (a certain number of days, weeks, etc)
-- if coverage is provided for damage to the rental car, is coverage limited to the value of your personal vehicle or will it cover the actual value of the rental vehicle (if more).
These questions can only be answered by Geico -- you must contact your representative to discuss details of your own particular policy and if or how it may cover you for a rental car from Hertz in Puerto Rico.
Hope this helps.