AWS Aurora Postgres Certificate Import

I am busy configuring the oracle_fdw to access data from on-premises Oracle databases in AWS RDS Aurora Postgres databases. When using a listener with a TCP port the connection works and the data is available.

However when using a listener using TCPS the connection fails with the below error: ERROR: connection for foreign table "<TABLE_NAME?" cannot be established DETAIL: ORA-12537: TNS:connection closed SQL state: HV00N

Is it possible to import our organization root certificates into the "ssl_cert"file" to enable TCPS connections?