[thelastdamnbatch]

I have researched google but was looking for a first hand account as all of the references have conflicting accounts as to how the potassium affects the taste of the beer.  Some say it doesn't, some say it's unpalatable, some say it's salty, so perhaps potassium is perceived differently by different people.

https://books.google.com/books?id=hBO3N5qLTEIC&pg=PA216&lpg=PA216&dq=adding+potassium+chloride+to+beer&source=bl&ots=L6aZirZSVs&sig=Et9vmgPLQEkgxy_8uSTdS6AxJ5Y&hl=en&sa=X&ved=0ahUKEwj67oefnorLAhUFPz4KHaIzBOgQ6AEIJDAB#v=onepage&q=adding%20potassium%20chloride%20to%20beer&f=false

https://www.morebeer.com/articles/treating_homebrew_water

https://books.google.com/books?id=_M2QAwAAQBAJ&pg=PT144&lpg=PT144&dq=adding+potassium+chloride+to+beer&source=bl&ots=qvtFrW6D_j&sig=Q3xFlyepBKbjeVo50ZbqY3SO7sA&hl=en&sa=X&ved=0ahUKEwj67oefnorLAhUFPz4KHaIzBOgQ6AEIWDAJ#v=onepage&q=adding%20potassium%20chloride%20to%20beer&f=false

[wingnut]

For the most part... I think how much KCl you add depends on what you are after. ... add a little and you wont really know it is there.  A bit more, and you dont know it is there... but some flavors shift and might be brighter or more muted.  Add enough, and you have invented the first  potato chip beer.   

I did some looking to see if there was a rational behind using K instead of Na, and found the article here to be interesting:

http://www.eufic.org/article/en/artid/salt-potassium-blood-control/

I still am not big on adding essentially table salt to brewing water.    It kind of reminds me of adding table salt to an IPA... It changes things, just not how I enjoy it.  (but my boss loves it... so what do I know!)   

In the end, if you are going to add one vs the other, it appears we get plenty of Na in our diet.  K, we need a bit more, so add it and we can drink more beer for our health!