qtcreator run environment for external dll

I have static library subproject which depends on external dynamic libraries.
I can successfully export external lib files to the main project for linking, but can't find a way to say qtcreator to add dll directory to the PATH during application run.
After reading documentation I expected that next code will work"

Export {
        Depends { name: "cpp" }
        Properties {
            condition: qbs.targetOS.contains("windows")
            cpp.systemRunPaths: [mylib.sourceDirectory +"/dll"]
            }
        }
    }

But it not works. Same for `cpp.libraryPaths`.

Probably this is not a bug, but just unclear documentation.

Thank you.