oca-technical/odoo-bringout-oca-rma-rma_reason/rma_reason/views/rma_portal_templates.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>

    <template id="portal_rma_page" name="My RMA" inherit_id="rma.portal_rma_page">

        <xpath expr="//div[@id='product_information']" position="inside">
            <div class="col-12 col-md-6 mb-4 mb-md-0">
                <div t-if="rma.reason_id" class="row mb-2 mb-sm-1">
                    <div class="col-12 col-sm-4">
                        <strong>Reason</strong>
                    </div>
                    <div class="col-12 col-sm-8">
                        <span t-field="rma.reason_id" />
                    </div>
                </div>
            </div>
        </xpath>
    </template>
</odoo>