thank you @Ray for reply.
yes, Manager is exist but the requirement is what i am trying to implement.

i have modified code (as per what i understand from link provided) but it is still not showing on user's form view, please check what i am missing or doing wrong here.

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<!-- Define a new view for inherited model -->
<record id="view_custom_res_user_form" model="ir.ui.view">
<field name="name">custom.res.users.form</field>
<field name="model">res.users</field>
<field name="inherit_id" ref="base.view_users_form"/>
<field name="arch" type="xml">
<xpath expr="//field[@name='partner_id'][1]" position="after">
<xpath expr="//field[@name='partner_id'][2]" position="after">
<field name="supervisor"/>
</xpath>
</xpath>
</field>
</record>
</odoo>

regards

The error in Odoo.log file as below:

Error while parsing or validating view:

Element '<xpath expr="//field[@name=&#39;partner_id&#39;][2]">' cannot be located in parent view

View error context:
{'file': 'd:\\program files\\odoo '
'17.0.20240101\\server\\odoo\\custom_addons\\brb_customizations\\views\\res_users_view.xml',
'line': 2,
'name': 'custom.res.users.form',
'view': ir.ui.view(1338,),
'view.model': 'res.users',
'view.parent': ir.ui.view(162,),
'xmlid': 'view_custom_res_user_form'}

.

sorry @Ray, by mistake i posted above error in Odoo.log please ignore it, it was because of before my posted code in your reply.

my first Comment to your Answer is valid, the 2nd one in which i posted error in Odoo.log is not.
waiting for your reply on my first Comment.
regards

In your first comment, you have an xpath inside an xpath and this is not supported.

If you wish to place your field after the second partner_id just reference the second partner_id - you don't need to reference the first at all

@Ray
i have check with code below, its not even start Odoo Server and showing errors in odoo.log file as below:
-------
Element '<xpath expr="//field[@name=&#39;partner_id&#39;][2]">' cannot be located in parent view

View error context:
{'file': 'd:\\program files\\odoo '
'17.0.20240101\\server\\odoo\\custom_addons\\brb_customizations\\views\\res_users_view.xml',
'line': 3,
'name': 'custom.res.users.form',
'view': ir.ui.view(1338,),
'view.model': 'res.users',
'view.parent': ir.ui.view(162,),
'xmlid': 'view_custom_res_user_form'}
--------

modified code as per your instruction:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<!-- Define a new view for inherited model -->
<record id="view_custom_res_user_form" model="ir.ui.view">
<field name="name">custom.res.users.form</field>
<field name="model">res.users</field>
<field name="inherit_id" ref="base.view_users_form"/>
<field name="arch" type="xml">
<xpath expr="//field[@name='partner_id'][2]" position="after">
<field name="supervisor"/>
</xpath>
</field>
</record>
</odoo>

please advice and help.
regards