Hi,
If you are supplying certain services from the UK to a business in the EU then the the services would be outside the scope of UK VAT and would be accountable by the business there.
However as the UK is no longer in the EU and you are not VAT registered there is no requirement to state on the invoice that it is a reverse charge sale.
You can see see the guidance here:
Reverse charge
The place of supply rules for services
Thank you.