Can anyone help me with the use and possible value of this bottle. There is only a K on the bottom so I think it may be handblown unknown 1860 to 1880's or GW Kearn's & Co 1860-1868.
Looks like either Kearns & Company, Zanesville, Ohio (1864-1876) and/or Kearns, Herdman & Gorsuch, Zanesville, Ohio (1876-1886). My source is this. https://www.glassbottlemarks.com/bottlemarks-3/ Not sure about the value. It has a nice design on it but would be worth more with some lettering embossed on it.
The K is not a trademark in this case unfortunately. Many bottles have random letters on the base that don't relate to the company that made them. The reason I say that for this bottle is because it's a bit newer than the Kearns trademark. Judging by the style and manufacture of the bottle I can pretty much guarantee your bottle dates from 1895-1920 (likely 1900-1915).
If it has manganese (pre WW-1) you could try to purple it up in the sun. Then someone who wants a window bottle probably 5-10$ depending on sunlight may take a few years unless you have a box and light.