account_retencion_ar/view/invoice_line_form.xml

<?xml version="1.0"?>
<data>
    <xpath
        expr="/form/notebook/page[@id='general']/group[@id='taxes_deductible_rate']"
        position="after">
        <label name="ganancias_regimen"/>
        <field name="ganancias_regimen"/>
    </xpath>
</data>