Libretime has to be configured to use a non SSL stream, then in the website you must use the SSL configured port. Check this website: https://basatisound.com as an example.
/etc/icecast/icecast2.xml
<listen-socket>
<port>8000</port>
<!-- <bind-address>127.0.0.1</bind-address> -->
<!-- <shoutcast-mount>/stream</shoutcast-mount> -->
</listen-socket>
<listen-socket>
<port>8443</port>
<ssl>1</ssl>
</listen-socket>
Take into account that the icecast default installation does not support SSL , so you’ll have to compile it from xiph with SSL support.
Another possibility is to create a reverse proxy with apache. I did that on this site: https://97irratia.info