The rdbdirpassword attribute is required while integrating Identity Governance and Identity Manager.
After adding the rdbdirpassword in the Identity Manager Management Console > Advanced Settings > Miscellaneous the attribute is not added to the list
Identity Manager 14.x
There are two process, first one to add the rdbdirpassword attribute and the other one in case you need its value to be displayed encrypted
To add the rdbdirpassword to the Miscellaneous page
To generate the hash you can use the password Tool