Before creating the RFC, be sure that your SAP Solution Manager system trusts the Jira Server.
Please, request your SAP Basis or Infrastructure Team to set up the connectivity configuration.
Please follow the steps to create the RFC to Jira:
Call the transaction SM59 and create a destination of type G.
Specify your Jira server as target host.
In panel Logon & Security select basic authentication and maintain a user created in Jira that will be used for the synchronization process. Activate SSL settings.
Test the connection and check if the external tool can be reached.
Attention: Please be sure that all SSL Certificates are distributed between SAP Solution Manager and Jira in order to have the connection properly running.