To play the Witney Talking News with Siri say:
Hey Siri, play the Witney Talking News Podcast
That’s really all you need, but whilst you are listening there are a number of useful phrases that you can use:
To pause, say:
Pause
To replay something or skip ahead, you can say phrases like:
Jump back 30 seconds
Skip ahead 2 minutes
To alter the speed of the playback, you can say:
Play it slower
Play it twice as fast
There are more options too, including pause and resume, details of which can be found from Apple Support