Where is the option to enable "Follow Author" link in the About the Author profile?

On my old site I had the following four options in the ABOUT THE AUTHOR section below each blog post:

View author's profile More posts from author Follow author Message author

On my new site I have not found how to turn on the Follow author option.

Can you tell me where I can find that option. I want it on for all Authors.

I am assuming by choosing to Follow author the users would receive notifications by email and by notifications?

Thank you, Sean Carney