Chrome launch custom URI protocol handler

I have a URI protocol handler in the windows registry to launch an application.  How can I test/call that from the chrome address bar?   if I put in protocolname:parameters, chrome just performs an internet search.  I want to launch protocolname and the application specified in protocolname handler.

I have a 3rd party website that is able to launch the protocol.  They have a settings field to launch URL on a trigger.  I put in my protocolname:parameters in the URL field.  When triggered, this website opens a new tab and protocolname:parameters shows in the address bar and the protocol is launched.  Like I said, though, when I try to test by putting the same thing manually in an address bar, it triggers a search instead of launching the protocol handler.