Electronegativity of Potassium (Pauling)
It depends which electronegativity scale you choose to use.  There are a lot of different scales for comparing electronegativities of the elements.  I've included a list of 11 of them below if you're interested.  In any case here are the electronegativities reported for potassium using 5 different electronegativity scales.  All values are in "Pauling units" so that the numbers can be compared.  The Pauling scale is the most commonly used, so 0.82 would be a reasonable estimate for the electronegativity of potassium.


Pauling 0.82
Sanderson 0.45
Allred Rochow 0.91
Mulliken-Jaffe 0.73
Allen 0.734


On the Pauling scale, electronegativities range from around 0.7 to 3.98 (fluorine), so as expected, potassium is at the electropositive end.  None of these scales report a value of 1.

List of 11 Different Electronegativity Scales


Pauling Scale: (1932)  Obtains values by thermochemical methods
Mulliken Relation: (1934)  Defines a relation that depends upon the
orbital characteristics of an atom in a molecule. Mulliken
electronegativity is the numerical average of the ionisation
potential and electron affinity
Gordy Scale: (1946)  Defines electronegativity in terms of the
effective nuclear charge and the covalent radius. (Zeff)e/r         
Walsh Scale: (1951)  Relates electronegativity to stretching force
constants of the bonds of an atom to a hydrogen atom.
Huggins Scale: (1953) Alternative to Pauling's thermochemical
procedure
Sanderson Scale: (1955)  The ratio of the average electron density of
an atom to that of a hypothetical "inert" atom having the same number of electrons. This ratio is a measure of the relative compactness of the atom
Allred-Rochow Scale: (1958)  Defines electronegativity in terms of the effective nuclear charge and covalent radius. Like the Gordy scale but uses (Zeff)e/r2
Jaffe Scale: (1962)  Uses the electronegativity of orbitals rather
than atoms to develop group electronegativities for molecular fragments (e.g. $\ce{CH3}$ vs $\ce{CF3}$) that take into account the charge of a group, the effects of substituents, and the hybridization of the bonding orbital
Phillips Scale: (1968)  Defines electronegativity in terms of the
dielectric properties of atoms in a given valence state
Martynov &amp; Batsanov Scale: (1980) Obtained by averaging the
successive ionisation energies of an element's valence electrons
Allen CE Scale: (1992) Configuration energy (CE), the average
one-electron valence shell energy of the ground-state free atom, is
used to quantify metal-covalent-ionic bonding