RTS works on the web in two main ways. RTN websites and/or 3rd Party websites.
Additionally, if you have a 3rd party website, your web developer has many options to list your showtimes on the 3rd party site.
These include using API access to pull showtimes, direct linking from your site to site, or using an i-Frame.
Here are some examples of each (The RTN Page, the WebApp, and 3rd Party Websites/API).