Final bit to configure Oracle SSO with Apex/HTMLDB application is to create New Authentication Scheme as “Oracle Application Server Single Sign-On (Application Express Engine as Partner App)”
I assume you have configured/Installed SSO with Apex, now login to apex application against which you want to use SSO authentication scheme.
Apex/HTMLDB is all GUI (Graphical User Interface) so you can configure/define new authentication scheme in Apex very easily.
On browser type URL http :// servername / pls/ apex
Enter your Worspace Name, UserName & password and you will see below screen
On this screen click on Shared component of Apex Application and it will take you to shared component. As we are interested in Security component (Authentication) so click on “Authentication Scheme” , you will be in Authentication Schemes page of Oarcle Apex / HTMLDB
From here click on “Create” button. After few screens you have to select Oracle Application server Single Sign-On (Application Express Engine as Partner Application) Now use this authentication scheme in your application .