Hi Budi,
I suppose that you mean a new REIP RERAPP-Procedure introduced with EhP 5 for ERP 6.0.
Besides this mentioned above EhP requirement, there is two more steps you need to take care of:
1. Activate Business Function RE_GEN_CI_3 using transaction SFW5.
2. Switch ON the REIP procedure in RE-FX Customizing using transaction RERACUST (see screen shot from Srini: Accounting -> Automatically Generated Accounting Documents -> Allow Integrated Posting)
Best regards,
Siarhei Kozyrau