What is the reference number needed for the Tax Info in iTunes Connect?
The instructions state if you're a foreign individual who is the single owner of a disregarded entity that is not claiming treaty benefits as a hybrid entity, with respect to a payment, and the account to which a payment is made or credited is in the name of the disregarded entity, you should write the name and account number of the disregarded entity on line 7 "Reference number" in order to inform the withholding agent of this fact.