For example, the whole type system is based on .NETs type system. interfaces, subtyping and generics, properties and indexed properties, which are quite different on the JVM and other platforms.
F# usually relies on having attributes (annotations in Java) for compatibility with other .NET languages like C# where certain features did not fit into the OCaml syntax and semantics cleanly. These also wouldn't transfer over to other platforms very well.
Some features which F# has that could transfer over to other platforms include measure types, active patterns, and type providers. I believe some of these have already made it to other languages. Gosu, for example, on the JVM had a feature similar to type providers before F# got them, so you could argue that F# borrowed that feature.