Results are presented of high-resolution transmission measurements using pure natural K metal samples. The measured total σ vs E to 400 keV is given, and resonance parameter evaluations are given for 65 resonances below 200 keV. The isosopte assignments, A=39 or 41, are mainly based on recent unpublished measurements of Good and Harvey at the Oak Ridge electron linear accelerator using separated K isotope samples. Values of level strengths, agΓn, are mainly based on transmission dip area analysis, which with evidence from the resonance shape and peak cross sections permits assignment of l and J for most resonances, and A for many of the resonances not identified in the separated isotope measurements. We obtain for the s and p strength functions: 104S0=(0.66+0.63- 0.30),(0.78+1.08-0.41), and 104S1=(1.8+0.7- 0.5) and (2.4+1.3-0.8) for 39K and 41K, respectively.