What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
If you are referring to the actual web builder Squarespace, then you might need to contact them if they have a widget or plugin for a Facebook like function.
If you are referring to how to add a Facebook like option page in your JotForm form, then that should be possible by adding this widget in your form: https://widgets.jotform.com/widget/facebook_like_box. To add a widget to your form, you can follow this guide: https://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form
If you are embedding the form to your Squarespace website, you can also follow this guide: https://www.jotform.com/help/37-Adding-Form-to-Squarespace
I hope that helps.