Translate a Ghost site

What you need

Administrator access to your Ghost admin, on Ghost(Pro) or a self-hosted install.
Nothing in the theme. Code injection is a setting, not a template edit.

Where the snippet goes

Copy your snippet

Open your site in the Verbafy dashboard and copy the embed snippet.

Your page, before </body>

<script
  src="https://cdn.verbafy.app/widget.js"
  data-site-id="site_abc123"
  data-api-key="pk_live_your_key"
></script>

Open code injection

In the Ghost admin, open Settings, then Code injection. Older versions of the admin put it under Settings, Advanced, Code injection.
Paste it into Site Footer

Paste the snippet into the Site Footer field and save. Ghost renders it before the closing </body> tag on every page of the site.

Check it is working

Open your site. The switcher is in the bottom right corner.
Switch language, then open a post. The choice is remembered.

Worth knowing on Ghost

The Ghost admin is out of scope by design

Site footer injection is part of the theme's output. The admin at /ghost/ is a separate application that does not render your theme, so it never loads the snippet and never spends your word allowance.