auth_supplier/views/auth_supplier_view.xml
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>
<template id="auth_supplier.fields"
inherit_id="auth_signup.fields"
name="Auth Signup/ResetPassword form fields">
<xpath expr="//div[@class='form-group field-login']" position="before">
<div class="form-group field-type">
<label for="account_type" class="control-label">Account Type</label>
<select class="form-control" name="account_type">
<option value="customer" selected="selected">Customer</option>
<option value="supplier">Supplier</option>
</select>
</div>
</xpath>
</template>
</data>
</openerp>