  Far ultraviolet (FUV) emission lines from dwarf stars are important driving
sources of photochemistry in planetary atmospheres. Properly interpreting
spectral features of planetary atmospheres critically depends on the emission
of its host star. While the spectral energy distributions (SEDs) of K- and
M-type stars have been extensively characterized by previous observational
programs, the full X-ray to infrared SED of F-type stars has not been assembled
to support atmospheric modeling. On the second flight of the Suborbital Imaging
Spectrograph for Transition-region Irradiance from Nearby Exoplanet host stars
(SISTINE-2) rocket-borne spectrograph, we successfully captured the FUV
spectrum of Procyon A (F5 IV-V) and made the first simultaneous observation of
several emission features across the FUV bandpass (1010 - 1270 and 1300 - 1565
\r{A}) of any cool star. We combine flight data with stellar models and
archival observations to develop the first SED of a mid-F star. We model the
response of a modern Earth-like exoplanet's upper atmosphere to the heightened
X-ray and extreme ultraviolet radiation within the habitable zone of Procyon A.
These models indicate that this planet would not experience significant
atmospheric escape. We simulate observations of the Ly$\alpha$ transit signal
of this exoplanet with the Hubble Space Telescope (HST) and the Habitable
Worlds Observatory (HWO). While marginally detectable with HST, we find that H
I Ly$\alpha$ transits of potentially habitable exoplanets orbiting high radial
velocity F-type stars could be observed with HWO for targets up to 150 pc away.
