Vijay,
An "Application" in BPC 7.x is called "Model" in BPC 10.x. Application Parameters are therefore same as Model Parameters and they're set under transaction SPRO -> Planning and Consolidation -> Configuration Parameters -> Set Model Parameters. If your BAdI filter is "POSTPRIMCOST_TO_ERP" and RFC destination of the ECC system you're retracting to "EUBCLNT100" then you seem to have already set the Application Parameters. Please provide detailed steps you've performed so far to help you with troubleshooting the problem.
Thanks,
Rajesh