I believe that NinjaKit currently doesn't do @require. Here's an example I made, that works in Firefox/GreaseMonkey and not in Safari/Ninjakit:
// ==UserScript==
// @name DEBUG
// @include http://localhost/Library.html
// @require file:///Users/#######/Sites/hello_world.js
// @require http://localhost/~#######/hello_world.js // EITHER WAY
// ==/UserScript==
alert('activated');
hello_world();
# hello_world.js
function hello_world(){
alert('Hello World!');
}
Either as a "remote" address or a local file, it worked fine in GreaseMonkey and failed in Safari. It's hard to get the ins-and-outs of NinjaKit currently, in my experience.