Kiltie was a term refering to one who wore a kilt. (TV: The Wheel in Space)
Scottish Highlander Jamie McCrimmon spent his time travelling with the Second Doctor wearing his kilt, even when it was too cold to do so. (TV: The Highlanders, The Abominable Snowmen, et al)
During a trip to Edinburgh in 1645, Nardole wore a kilt complete with a Sporran and tam o' shanter before being told to remove them by the Twelfth Doctor. (PROSE: Plague City)
Highland soldiers fighting as part of the British Army in World War I wore kilts. (AUDIO: The Mouthless Dead)
The Brigadier wore a kilt meeting the Fourth Doctor, Sarah Jane Smith and Harry Sullivan in Scotland. He explained to Sarah Jane that the reason he was wearing it was that his family was from the clan Stewart. (TV: Terror of the Zygons)