How do I get a standard retaining ring model to fit in a pre created groove?

Hi,

I am looking to fit a standard retaining ring model to fit in a groove I created before. I am not using the create groove feature of Solidworks. I can mate the part alright but the thing is supposed to stretch and fit into the groove. How can I achieve this? I am very new to SW.

Thanks

S. M.

SolidworksAssemblies