You need to enable BPAY by following these steps:
Click Settings > Payments.
In the BPAY section, click the Enable button next to the relevant Group or Individual practitioner. If the relevant practitioner is not on the list, you can add them to the list and enable BPAY for them by following these steps:
In the BPAY section, click Add New.
Select the practitioner from the drop-down menu.
Once enabled, the BPAY reference number and other details will automatically appear on the invoice when you print or email it.