There are 11 possible solutions to the Harmonization contest using an excerpt from Foote and Spalding (1905).  

Seven of them are poor, using a iii6 following a V or a V6 (the effect is of an unchanging chord with nonharmonic tones).

  • I IV V6 iii6 I
  • I IV6 V iii6 I
  • I IV6 V6 iii6 I
  • I vi V iii6 I
  • I vi V6 iii6 I
  • I vi6 V6 iii6 I
  • I vi6 V  iii6 I

The remaining four are not particularly good either; as I indicated in the contest post, the best solution, not allowed by Foote and Spalding, would be a simple V under the entire second measure.

  • I IV  V6 iii  I
  • I IV6 V6 iii I
  • I vi V iii I
  • I vi6 V6 iii  I

The point of the contest was to illustrate how a tuned melodic interval (the minor third between 2 and 7) can influence harmonic choices. In my opinion this applies from at least Josquin’s time, possibly earlier, until today. In Josquin’s practice, the application of musica ficta could alter melodic intervals and thus harmonic choices (had that 7 been flatted, for instance, then the 2 should have been harmonized by a ii or a ii6 chord).