In general and important for you to know is that any invoice request is a matter between you (the organiser) and the guest only.
RSVP is acting solely as the payment processor and platform for the transaction (Imagine RSVP to be the credit card machine in your location).
Once a guest is requesting an invoice, you have two options:
A: You can send an invoice directly from your own system and/or according to your own standards and rules. You can find all guest info in the booking overview and you can always reach out to the guest to enquire further invoicing details. Here it depends on your rules if you have to disclose VAT (and how much). All RSVP prices are to be considered incl. VAT. Make sure that the invoice you are issuing is including all fees, even if you chose the option for the guest to pay for the fees. Invoices coming from the event organiser always have to include all fees, since RSVP will provide the organiser with a separate invoice for the fees. If you require this 'fee invoice' please contact firstname.lastname@example.org
B: You can use our support action 'generate invoice' that you can find next to the guest in the booking overview. This is simply an easier way for you to generate an invoice and forward it to the guest. Important here is also that RSVP is only acting as a platform to generate the document and is not able to send anything to the guest. (Imagine RSVP to be the 'printer' only). Before generating any invoice, make sure that all your account details are correctly added in your profile settings in the RSVP admin. Once your correct VAT amount is provided, the invoice will automatically state the correct amount. You can also adjust the guest information with the action button on the right saying 'Update invoice'.
As for the RSVP booking fee of 5% that is applied to any booking, you can easily download the Accounting Report from the event admin, which enclosed the fee according to the payout of the total sales at the end of the event.