Hi indieamy,
All you have to do is edit the footer.hbs file (Documents ▸ Publii ▸ sites ▸ YOUR_SITE ▸ input ▸ themes ▸ simple ▸ partials) by adding the following code:
<a href=”URL to Spotify” aria-label=”Spotify”>
your icon here
</a>
To preserve the custom code changed from being overwritten the next time your theme is updated, please make sure you have created override files, which are essentially copies of the existing theme files and are stored separately → https://getpublii.com/dev/theme-overrides/
