account_voucher_comision/views/res_config_settings_view.xml

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

        <!-- FORM CONFIG -->
        <record id="view_voucher_config_settings_form" model="ir.ui.view">
            <field name="name">voucher.config.settings.form</field>
            <field name="model">res.config.settings</field>
            <field name="arch" type="xml">
                <form string="Configuración Comisión Voucher">

                    <group>
                        <field name="voucher_comision_porcentaje"/>
                    </group>

                    <footer>
                        <button string="Guardar"
                                type="object"
                                name="execute"
                                class="oe_highlight"/>

                        <button string="Cancelar"
                                special="cancel"/>
                    </footer>

                </form>
            </field>
        </record>

        <!-- ACTION -->
        <record id="action_voucher_config_settings" model="ir.actions.act_window">
            <field name="name">Configuración Comisión Voucher</field>
            <field name="res_model">res.config.settings</field>
            <field name="view_mode">form</field>
            <field name="target">inline</field>
        </record>

        <!-- MENU -->
        <menuitem id="menu_voucher_config_settings"
                  name="Comisión Voucher"
                  parent="account.menu_finance_configuration"
                  action="action_voucher_config_settings"
                  sequence="50"/>

    </data>
</openerp>