Trapcode Particular/Obscuration layer Matte Choke in After effects

Hi

I'm using an obscuration layer on a large particular project.  I am able to place it properly in space and obscure the desired particles but I am unable to apply a blur or choke to the Solid used for obscuration.  In the project, the point of obscuration is out of focus and the harsh/sharp edge created ruins the effect I am going for.  I have tried to apply a choke or edge blur with a plain solid and in a precomp.  All aspects of the desired effect are working except the choke.  Is there anyway to achieve a blurred edge to the obscuration layer effect?

Thanks,

C