Can you explain a bit more how your application looks like? Do you have a picture about such a weigh feeder, so that we can see it? It's difficult to imagine your concrete application, at least for me.
You must distinguish to issues, vibration, as origin of resonances and dampening, which dampen these resonances. Even if vibration is very low, without any dampening heavy resonances can occur! So, what could help you is to add some mechanical dampening to your way feeder, like shock-absorber do it in a car.

Kai