First make sure you're in the Comment mode (you can access it either from a link, from the Project manager or from the Inspect mode.)
Just click on the design canvas to create a pinpoint annotation, drag over the design to highlight an area or start writing a comment in the general comments section in the left sidebar.
How to mention someone in a comment?
Then use the @Symbol to mention anyone from your team.
Once the first letter behind the @ Symbol matches a letter in the name of someone on the list of your team members, you should see a dropdown (like below). Either finish writing the exact name of someone from your team or select someone from the dropdown.
Then just make sure to finish adding the comment by pressing Enter or the button "CREATE ANNOTATION".
NOTE: It doesn't matter if the @mention is at the beginning, the end or in the middle of your comment. It works always.
Will I get notified if someone mentions me?
If you have e-mail notifications enabled in your account settings, you receive an e-mail with every new comment in Avocode.
If you're mentioned in the comment, you will see that in the message preview in the e-mail.
If you have the Avocode Slack integration, mentions will be bold-highlighted in the comment preview of each Slack notification in your Avocode channel (or channels that you have connected to Avocode projects).