In Kotlin, there’s no checked exceptions, no exceptions have to be declared and you aren’t forced to catch any exception, though, of course, you can. Even when deriving from a Java class, you don’t have to declare exceptions that a method throws.
@Throws(SomeException::class) is just intended for Java interoperability, which allows one to write a function with throws in Java signature, so that in Java it will be possible (and necessary) to handle the exception.
Instead, public API exceptions should be documented in KDoc with @throws tag.