The notes sold at market price for gold, not necessarily one to one, but with a cut. The notes would anyway be worth more than the corresponding gold due to ease of use.
that would work for a while but its sort of ponzish since it relies on new money constantly coming in to pay for the services of existing customers. what happens when the market is saturated with notes? where do they get the money necessary to run day to day operations like paying the employees who operate the counter for exchanging notes for physical and printing new notes to replace worn out notes.