1. If the trust zone of the U-Shield digital certificate signature is not checked completely, you should reapply for digital signature. Insert U shield or digital certificate first, then open the PDF application form, click the signature column, and the basic information of digital certificate will pop up automatically.

2. Click the "Signature" button, and the system will automatically prompt you to save the PDF spreadsheet. After selecting the storage path, click the Save button.

3. The system will automatically pop up the "Verify U Shield Password" box. After entering the password accurately, click the "OK" button. If there is no error prompt, the electronic signature is completed.