Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
As @DBDukes is indicating, many of the Channels(apps) have their own Live TV. This is not over-the-air channels per-se (antenna tv/local channels). So for the Roku Channel, their Live TV starts at channel 115 and ends at 1190.
When you are in Roku Channel Live TV and are watching a show, just press the Left Arrow button on your remote and that will show you the channel guide where you can navigate to other Live TV channels.
Each Channel(app) that offers Live TV may have a different button to access the guide. Not standard across the different free Channels. Also the channel numbers of Live TV channels may be completely different and offer different content.