Automate reference # column?

I used a project timeline template with a gantt chart and I liked the column "Ref #" all the way to the left hat numbers out each column. I am editing the template but when I add a row it doesn't show a new number for that column, it's blank....

How can I get it so it can automatically add new numbers sequentially to that column whenever I add a row? Thanks!

Screenshot 2023-03-24 at 11.16.20 AM.png


Answers