How to add sined-off-by message in git commit message when I use WEB IDE of gitlab?

Some projects require signed-off-by message, like a Signed-off-by: XXXX XXXX <xxx@xxx.com> in git commit messages.

When editing files on local machine, I can do it by using git commit --signoff command. It is very simple . But when editing files on gitlab’s WEB IDE interface, I must type it on commit message field by manually.

Is there any commit message template functionality ?