Seek {seconds}

I noticed in the API there is the control
POST /api/seek/{seconds}

I use the AppleTV to view all my recordings.
Using a Harmony Remote, is there any way to program a button to prompt the user the number of seconds (or minutes) to seek into the program?

No, because the seek command is an HTTP request sent to the Channels client, not a keypress.

Understood.
So the AppleTV player itself would need to understand that request, which it currently doesn't.

The appletv can accept the request I believe, but can the harmony remote send a http request in response to a button press?