Just checked with latest code in development should work in earlier versions:
Note that if you can
sqlplus username/password@database (using Radius)
you should be able to use sqldeveloper in the same way using OCI/Thick driver (see tools->preferences->database->Advanced (Use OCI/Thick driver) for the check box to use OCI/Thick tested, for example, with 220.127.116.11 instant client)
i.e. set up radius server and client, then oracle sqlnet.ora, then sqlplus [see core database administration documents], then sqldeveloper on top should be easy.
Authentication (using user name and password for each connection) via Radius authentication server has been verified over OCI/thick, where username is saved/stored for each attempt at authentication (the password can be saved (bad for security) or prompted). 'Challenge/response' mode is not supported.