I have a list of people that the user wants to contact. They can "Mark as done" when they have made the contact (then it goes to their follow up list 3 days later). Displaying the "Mark as done" button makes the list appear very long and fall off the page, so I hid it by default and only display it on user click of the contact.
In observing a user interacting with the list yesterday, they didn't realize they could click on a contact to mark complete.
What's the best way to indicate that they can mark as done by clicking on the contact? Or should a "mark as done" button/link be displayed by default?