Hello 1bluestar,
Welcome to the Apple Support Communities!
I understand that you have a Keynote presentation that you would like to share to you Apple TV using Home Sharing. To view a document or presentation on your Apple TV, you would need to use a feature called AirPlay. AirPlay will allow you to view what is showing on the display of your iOS device on your Apple TV.
About AirPlay Mirroring in OS X - Apple Support
Home Sharing is for viewing/listening iTunes media such as music or videos on separate devices or computers. For more information on Home Sharing, please use the attached article as a further reference.
iTunes: Setting up Home Sharing on your computer - Apple Support
Have a great day,
Joe