Squarespace's Code Injection feature lets you add scripts to every page's <head> without touching any files.
After signing up, copy your API key from your Findables dashboard.
In your Squarespace admin, go to Settings → Advanced → Code Injection.
In the Header text area, paste the following:
Replace YOUR_API_KEY with your API key and YOUR_SITE_SLUG with your site slug — both are in your dashboard.
Click Save. The script is now live on every page of your site.
Visit any page on your site, right-click → View Page Source, and confirm the script tag appears inside <head>.