You can verify the authenticity of a electronically signed document by opening the document with e.g. Adobe Acrobat Reader DC software. Using default settings Adobe Acrobat Reader DC does not have the Population Register Centre Root Certificate and will inform that signature has problems.
You can install Root certificate from Population Register Centre with these instructions:
- Download the root certificate from the Population Register Centre website: https://vrk.fi/en/ca-certificates
- Open Adobe Acrobat Reader DC
- Click Edit or Adobe Reader (OSX) » Preferences
- Select Signatures » Identities & Trusted Certificates » More
- Select Trusted Certificates » Import
- Click on Browse and select file you downloaded » Open
- First select certificate from Contacts and then from Certificates » Trust
- Select Use this certificate as a trusted root » OK
- Now software has installed Popular Register Centre certificate and will trust any signatures that have been signed with this certificate