vracoop_product_returnable/views/template.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

    <template id="product" inherit_id="website_sale.product">
    	<xpath expr="//a[@id='add_to_cart']" position="after">
    		<t t-foreach="product.return_product_ids" t-as="return_product">
                <div class="mt16 ">
                	<input checked="1" type="radio" t-att-id="return_product.id" name="consignes" t-att-value="return_product.id"/>
				  	<label t-att-for="return_product.name"><span t-att-title="return_product.name" t-field="return_product.name" style="display: block;" /></label>
                </div>
            </t>
    	</xpath>
    </template>

</odoo>