panel.<domain>.tk.conf

<VirtualHost *:80>
    ServerAdmin me@gmail.com
    ServerName panel.<domain>.tk
    ServerAlias www.panel.<domain>.tk
    DocumentRoot /var/www/panel.<domain>.tk/public
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>