SSL connection to AWS RDS Postgresql instance from windows client
If you are using PGAdmin, when you create a new connection there is a tab called SSL[1]. There you can input your pem file.

If you are using psql, put your pemfile on %APPDATA%\postgresql\ directory. See more details at the documentation[2].

Hope it helps.

References:


https://www.pgadmin.org/docs/dev/connect.html?highlight=ssl
https://www.postgresql.org/docs/9.2/static/libpq-ssl.html