I didn't see that option, but i must have overlooked.
Thanks!
Notes on profile
Sort:
Go to the profile page of who you want to reply too, it should already be on the tab 'Write a note' (that I have circled in green).
You'll see this page similar to yours (you might have to scroll down a bit).
Write your message then 'Post'.
Thanks 
Hi,
Can someone tell me how to leave a note on someone else's profile? I just got one and would like to reply.
THanks !