Function Style – How do I convert an argument list to a sequence of arguments?

I think that's a basic question, but I'm having trouble finding the answer in the documentation. thread is not what I'm looking for, I think.

Suppose I have a function f this requires an unspecified number of arguments:

    f[a, b, c, ...]

defined by a declaration like

f[lists__] : = ...

Suppose I have an argument list {A B C D},

How can I get that? f[a, b, c, d] from {A B C D}?

Many Thanks.