rma/website_rma/data/ir_model_data.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2020 Tecnativa - Ernesto Tejeda
     License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl). -->
<odoo>
    <data>
        <record id="rma.model_rma" model="ir.model">
            <field name="website_form_default_field_id" ref="rma.field_rma__description" />
            <field name="website_form_access">True</field>
            <field name="website_form_label">Request RMA</field>
        </record>
    </data>
    <function model="ir.model.fields" name="formbuilder_whitelist">
        <value>rma</value>
        <value eval="[
            'partner_id',
            'product_id',
            'product_uom_qty',
            'product_uom',
            'operation_id',
            'description',
            'state',
        ]"/>
    </function>
</odoo>