SKRATK    SKRATK    SKRATK    SKRATK    SKRATK    SKRATK    SKRATK    
          **********************************************
                    **************************
                              ******

SUBROUTINE SKRATK  (P, T, ACT, SDEN, RKFT, RKRT, ISKWRK, RSKWRK,
                    SDOT, SITDOT)
Returns production rates for the species and sites, using the
pre-calculated temperature-dependent rate coefficients RKFT, RKRT.

INPUT
P         - Real scalar, pressure.
               cgs units, dynes/cm**2
T(*)      - Real array, temperature(s); dimension is determined by
            the application program to be the total number of
            species temperatures, nominally 1.
               cgs units, K
ACT(*)    - Real array, activities of the species;
            dimension at least KKTOT, the total species count.
            The first KKGAS activities are mole fractions,
            the next KKSURF activities are site fractions
               (species density normalized by the site density;
                surface concentration in moles/cm**2 is
                ACT(K)*SITE_DENSITY / # sites per species), and
            the next KKBULK activities for bulk phase species
            should be from 0 to 1, and should sum to 1 for each
            phase.
SDEN(*)   - Real array, site densities for the site types;
            dimension at least NPHASE, the total phase count,
            but the subroutine only uses site phase entries,
            NFSURF <= N <= NLSURF.
               cgs units, moles/cm**2.
RKFT(*)   - Real array, forward reaction rates for reactions;
            dimension at least IISUR, the total reaction count.
               cgs units, depends on the reaction
RKRT(*)   - Real array, reverse reaction rates for reactions;
            dimension at least IISUR, the total reaction count.
               cgs units, depends on the reaction
ISKWRK(*) - Integer workspace array; dimension at least LENISK.
RSKWRK(*) - Real    workspace array; dimension at least LENRSK.

OUTPUT
SDOT(*)   - Real array, production rates of the species;
            dimension at least KKTOT, the total species count.
               cgs units, moles/(cm**2*sec)
            for 1,KKGAS, the production rate of gas-phase species,
            for KKGAS+1,KKGAS+KKSUR, the production rate of surface
            species,
            for KKGAS+KKSUR+1,KKTOT, the production rate of bulk
            species.
SITDOT(*) - Real array, production rates of the surface phases;
            dimension at least NPHASE, the total phase count, but
            subroutine only calculates entries for site phases.
               cgs units, moles/(cm**2*sec)