How can I know which underlying security an F share represents?

From my understanding, "F shares" are created by US broker-dealers to show quotes of foreign securities in USD (source: FAQ on F Shares – OTC Markets). If I know the symbol of an F share, is there a way I can know exactly which foreign underlying security the F share represents? By "exactly", I mean country/exchange/ticker information or even the ISIN of the underlying.

For example, I happen to know that RBGPF is the F share of the London Stock Exchange listing of Reckitt Benckiser Group Plc. (LSE symbol: RB, ISIN: GB00B24CGK77), but that is only because there is lots of information about this company around the internet. If I am looking at the F share of a thinly-traded and obscure security, it may be difficult to conclusively determine what the underlying security is, especially when the issuer also has multiple share classes, preferred stock issues, exchange-traded warrants, or rights issues. Previously, I used FINRA’s OTC Daily List to find the underlying securities, but not all F shares are on the list (probably because some of those F shares were created decades ago).

In other words, is there a central regulatory authority that registers F shares? If so, are the registration documents publicly available? If so, where can I obtain those documents? Note that I am not looking for third-party websites or resources. I am looking for the official source of information.