Hi @shubh802,
Drop-down lists are something you’d need to use a custom output payload for depending on the channel you’re using. You could specify the payload as json in your custom action, and fill the names of the doctors from your database/wherever you’re getting their names from
Just a note with regards to mentioning people in posts, please take a look at How to use Solutions & Mentions for guidelines; it’s helpful if you don’t mention multiple community members or members of the rasa team in your post.