I think I might have something here check this 1969 D out it's got another d right off to the top left I don't know if it's attributed anywhere but I don't even know what to look for these nickels I can see a whole my phone sucks it just won't take a good picture of it all
Wexler's only shows one '69 RPM Jeff Nickel, see if yours matches. Remember to check for the die markers also. https://doubleddie.com/1469129.html
That extra area that looks like a D is not from it being a mint mark let alone an RPM. A mint employee may have slightly scratched the die and that would make it raised on the coin. With wear from die use and then in circulation it will look like this. Barely noticeable and worth nothing extra.