Individual [F/Fe] vs. [Fe/H] trends. Top panels: [F/Fe] vs. [Fe/H] for the 50 solar neighborhood M giants (red circles) determined from the six K-band molecular HF lines (each panel) in the IGRINS spectra. All are scaled to the following solar abundances: A(F)_⊙ = 4.43 (Lodders 2003) and A(Fe)_⊙ = 7.45 (Grevesse et al. 2007). There is an evident increase and large scatter in [F/Fe] determined from the four reddest and strongest HF lines at 23 040.57 Å (R12), 23 134.76 Å (R11), 23 358 Å (R9), and 23 629.99 Å (R7) for stars with [Fe/H] ~ 0 dex and above (not evident in other lines)