  RR Lyrae stars are excellent tracers of stellar populations for old,
metal-poor components in the Milky Way Galaxy and the Local Group. Their
luminosities have a metallicity-dependence, but determining spectroscopic
[Fe/H] metallicities for RR Lyrae stars, especially at distances outside the
solar neighbourhood, is challenging. Using 40 RRLs with metallicities derived
from both Fe(II) and Fe(I) abundances, we verify the calibration between the
[Fe/H] of RR Lyrae stars from the Calcium triplet. Our calibration is applied
to all RR Lyrae stars with Gaia RVS spectra in Gaia DR3 as well as to 80 stars
in the inner Galaxy from the BRAVA-RR survey. The co-added Gaia RVS RR Lyrae
spectra provide RR Lyrae metallicities with an uncertainty of 0.25~dex, which
is a factor of two improvement over the Gaia photometric RR Lyrae
metallicities. Within our Galactic bulge RR Lyrae star sample, we find a
dominant fraction with low energies without a prominent rotating component. Due
to the large fraction of such stars, we interpret these stars as belonging to
the $in-situ$ metal-poor Galactic bulge component, although we can not rule out
that a fraction of these belong to an ancient accretion event such as
Kraken/Heracles.
