  Silicon spin qubits have emerged as a promising path to large-scale quantum
processors. In this prospect, the development of scalable qubit readout schemes
involving a minimal device overhead is a compelling step. Here we report the
implementation of gate-coupled rf reflectometry for the dispersive readout of a
fully functional spin qubit device. We use a p-type double-gate transistor made
using industry-standard silicon technology. The first gate confines a hole
quantum dot encoding the spin qubit, the second one a helper dot enabling
readout. The qubit state is measured through the phase response of a
lumped-element resonator to spin-selective interdot tunneling. The demonstrated
qubit readout scheme requires no coupling to a Fermi reservoir, thereby
offering a compact and potentially scalable solution whose operation may be
extended above 1\,K.
