OAF pages in APEX? Where is that idea come from?
What is your purpose? First, tell me that clearly ..
Check this blog post ->
http://apex4ebs.blogspot.com/p/integration-of-oracle-apex-and-e.html
That blog post above may help you.
Check this one also -> Extending Oracle E-Business Suite Release 12.1.3 and Above Using Oracle Application Express (APEX) (Doc ID 1306563.1)