In the structure of SF$$_4$$, the lone pair of electrons on S is in.

$$SF_4$$ has sulfur with 6 valence electrons forming 4 bonds with fluorine atoms and 1 lone pair, giving a total of 5 electron pairs. The electron geometry is trigonal bipyramidal.

In a trigonal bipyramidal arrangement, the lone pair occupies the equatorial position to minimize repulsion: in this position it has 2 interactions at 90° (with the two axial bond pairs) and 2 interactions at 120° (with the other equatorial bond pairs), whereas in the axial position it would have 3 interactions at 90° (with all three equatorial bond pairs). Since lone pair - bond pair repulsions at 90° are strongest, minimizing the number of 90° repulsions is preferred.

With the lone pair equatorial, it makes 90° angles only with the 2 axial fluorine atoms, the other 2 equatorial atoms being at 120°, resulting in two lone pair - bond pair repulsions at 90°.

Hence, the correct answer is Option A: Equatorial position with two lone pair - bond pair repulsions at 90°.