Opt-in checkbox on Woocommernce/Wordpress registration

I’m looking to add it in the new user form as way to have the user opt-in during registration.

Essentially as in your docs: https://help.klaviyo.com/hc/en-us/articles/4403349019163

Dumb question...if we tell a user that by signing up they are opting in to our mailing list, with the option of opting out later, is that legal in the US?

@yellaroot Hiya! What system are you using to register users? If it’s something Klaviyo has an integration with, then yes, you can add a checkbox. If not, you might need to speak with a developer to custom code something for you. 

@kaila.lawrence We are running your Klaviyo Wordpress/Woocommerce plugin. I actually am a developer and I can’t seem to find anything about adding a custom checkbox anywhere in your documentation. Would you mind pointing me in the right direction? 

@kaila.lawrence The checkbox shows up automatically on the check out page but, I would like to add a custom checkbox on the user registration form.

Sorry...this was marked as the answer but, does not answer the question.