I would like to put a different iframe field on every website. I have created a custom field but when I choose text area or other field looks like on the attachment after the <script> rest oh the code is visible on frontend website.
When I choose custom HTML the field is not available screenshot also in the attachment.
The field custom_html does not save the value in the database, so the helper function rwmb_meta() won't render the code on the frontend. You can use the field textarea or wysiwyg and bypass the sanitization to add any HTML tags. Refer to this documentation https://docs.metabox.io/sanitization/