To be able to digitally sign a document in Word or Excel you must have your certificate installed on your computer. If you haven't installed it yet please see how to install your digital certificate.
After installing please follow these steps to sign your document:
- Open your document
- Go to [File] click on [Info]
- On tje section Protect Document,/ Protect Workbook select a Add a Digital Signature
- The window [Signature Settings] will appear
- Choose the the signature purpose and click [Sign]
Veja aqui vídeo completo com a explicação da Assinatura em Microsoft Word