This is an old thread but for those of you in France, (like me), and who need this document badly, (as I do), you might like to know that there is nothing to stop you creating your own.
I have checked and there is no legal reason why you cannot communicate the basic details of your account, (account name, address, IBAN, BIC) and those of the banking institution to which your account pertains, (bank name, registered address), formatted in such a manner as to resemble a traditional RIB. There is even French web site which has a script which does this for you. I personally would not use the site, (I am not keen to put my details out there to be stored in some third party database), but if you search for "creer votre propre RIB", you'll find it. Alternatively, use the model I made above but be aware that Bunq may object to you using their logo. I cannot imagine that they would, but you never know.
For those of you stuck in French admin hell, I hope that helps.