You have experience with Tcl--certainly you're beyond the "When all you want is to run a Tk application" level. Someone hands you a .kit file; what do you do with it?
Experienced Tcl'ers know to run it against Tclkit, that is, invoke
tclkit some_application.kit
As Tclkit is an important idea, perhaps you'll want to learn it, or at least enough about it to download the executable and launch the application that interests you. If not, perhaps you can find someone with more experience to "unpack" some_application.kit for you and forward the *.tcl sources (and perhaps other texts and binaries) it packages. At this level, you see, Tclkit is a way to wrap up an application into a single file; it can equally easily be unwrapped into pieces that might be more comprehensible to a newcomer to Tclkit.