To sign the signature line, ensure first that the data on the spreadsheet is ready and there’s nothing you or the signer has to change.
Once you confirm that there’s nothing you have to edit, double-click on the signature line until an Excel ‘Sign’ window will show up.
Here, you can either type your name on the signature line (if you’re the signer) or insert a picture to use as the signature.
You could also add additional details by clicking on the ‘Details…’ box.
Once you’re satisfied, click on the ‘Sign’ box.
You can still proceed, however, by clicking on the ‘Yes’ option.