  We shortly review our new superfield formalism in the framework of Fujita,
Kugo, Ohashi 5D conformal supergravity, in particular with an $S^1/Z_2$
orbifold. The radion of the fifth dimension is embedded in two related
superfields, a chiral and a general multiplet and is linked to the radion
superfield of rigid SUSY. The superspace action of the gauge sector is of the
Chern-Simons type. We also present the superspace action for hypermultiplets
and discuss the role of compensators. The presented formalism should be very
useful for applications. We demonstrate this for obtaining the RS solution.
