Add ressource custom field value with PSI 2013

Hi.

I'm learning how develop with the Project Server PSI 2013. I succeed add project custom field value, via the SetCustomFieldValue method, but that method doesnt exist in the EnterpriseRessource class.

So i add my value directly in the FieldValue property but i have an exception saying that the field doesnt exist, but he's in the context custom field collection when i update the Enterprise Ressource Collection.

Someone has a sample of adding a custom field value in a ressource via the PSI of Project Server 2013 ? For example in the RBS field.

Regards.