How to create a custom field to a core module in suitecrm-8?

I’m trying to create a custom field in the contacts module. I want this field to be added to the contacts table directly and not in contacts_cstm so I avoid using studio. For this purpose I use the strategy of using the Vardef Extensions

I have created a file in this location:

public/legacy/custom/modules/Contacts/Ext/Vardefs/custom_field.php

with this content

<?php

$dictionary['Contact']['fields']['custom_field'] = array(
     'name' => 'custom_field',
     'vname' => 'custom_field,
     'type' => 'bool',
     'default' => 0,
     'required'=> false,
);

When repairing I hope it identifies this difference and allows me to synchronize by adding the new field

But when repairing I do not get any message that there is a new field to add

What is the correct way to add a custom field to a core module in suitecrm? Thanks in advance

Your path should be

public/legacy/custom/Extension/modules/Contacts/Ext/Vardefs/custom_field.php

You are missing the Extension folder

thanks for the clarification. Applying your observation solved the problem