  In a recent review by Anderson and coworkers\cite{Vanilla}, it was pointed
out that an early resonating valence bond (RVB) theory is able to explain a
number of unusual properties of high temperature superconducting (SC)
Cu-oxides. Here we extend previous calculations \cite{anderson87,FC
Zhang,Randeria} to study more systematically low energy physical properties of
the plain vanilla d-wave RVB state, and to compare results with the available
experiments. We use a renormalized mean field theory combined with variational
Monte Carlo and power Lanczos methods to study the RVB state of an extended
$t-J$ model in a square lattice with parameters suitable for the hole doped
Cu-oxides. The physical observable quantities we study include the specific
heat, the linear residual thermal conductivity, the in-plane magnetic
penetration depth, the quasiparticle energy at the antinode $(\pi, 0)$, the
superconducting energy gap, the quasiparticle spectra and the Drude weight. The
traits of nodes (including $k_{F}$, the Fermi velocity $v_{F}$ and the velocity
along Fermi surface $v_{2}$), as well as the SC order parameter are also
studied. Comparisons of the theory and the experiments in cuprates show an
overall qualitative agreement, especially on their doping dependences.
