In 1920, "Horne Daily News" display ads ran regularly in the local Pittsburgh newspapers. On September 29, 1920, the department store's advertisement noted that their toy department personnel had heard an "air concert" transmitted locally by Frank Conrad over station 8XK, which inspired Westinghouse executive H. P. Davis to have his company set up a regular radio broadcast service. (Davis saw the advertisement that ran in the Pittsburgh Sun, but it also appeared in the same day's Pittsburgh Press.)
The original scan for the 1945 Horne's KDKA 25th anniversary advertisement below is also located at the Google newspapers archive site.
Pittsburgh Post-Gazette, November 2, 1945, page 9: