How much additional potassium to take on LCHF?

Thats a question thats best asked of your doctor, thats the very best advice I can offer you on this specific issue.

When you have your blood tested [CBC ] you should get results for sodium and Potassium. Its unusual to find yourself "out of specification".

I wouldn't consider supplements unless my blood tests showed I was deficient and the GP recommended them.
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I get cramps if I don't get enough - took me AGES to work out that potassium supplements were needed.

The first symptom I get is a weird sore throat in the morning. It clears up by 11 am usually (just about the time I have digested my breakfast, funnily enough). A few times I have even had a swollen pale patch like a bobble on my tonsil. Always disappears as the morning progresses. It happened for months at one time, but I would usually only expect it occasionally - and now I know to pop a supplement for a few days.

The next symptom is cramps, usually in the night. More likely in hot weather.

My attitude is that while I don't want too much potassium, I certainly don't want daily sore throats and nightly cramps.

So I keep a pot of potassium supplements handy and pop a pill daily in hot weather, and a couple of times a week through the rest of the year. Of course I forget but that sore throat is a very handy reminder.

Unfortunately, we don't all get the same signals, so I think we just have to apply common sense... which ain't always easy!

My Mum gets night cramps if her potassium levels are low. Before T2 she would eat a banana a day, now she will have 200ml only of coconut water and/or eat some form of chocho (west indian watery veg that can be cooked or grated into salad).
I would look for ways to step up vits n minerals via food.... makes things interesting.

A good article here by Dr Kendrick on this and very interesting comments in the posts below the article

http://drmalcolmkendrick.org/2013/03/04/potassium-your-invisible-friend/

Best

Dillinger

Having read that article, I am upping my intake. I'm obviously skirting too low at the moment.

Thank you @Dillinger

Yes, very interesting, thanks - as an aside I loved this comment in his blog

I immediately liked this finding. Mainly because it was almost completely unexpected, and unexpected findings are always far more likely to be correct than expected findings.

It is all to do with balance between sodium and potassium.
If the balance is wrong and that is often caused by too much sodium then your blood pressure will increase as water is drawn into the circulation to try to even out concentrations .http://www.bloodpressureuk.org/microsites/salt/Home/Whypotassiumhelps
Yet people are suggesting taking both salt and potassium thus adding to both 'sides' .
Sodium potassium concentrations are also crucial in that the balance is essential for neurons to fire properly (easy primer)https://faculty.washington.edu/chudler/ap.html

Too little potassium is bad, and at extremes can be life threatening. (been there with my mother, very scary at the time)
But too much is also bad and it can build up, especially if the kidneys are unable to deal with it. This time it's my father that has exactly this problem. In part because he takes drugs for heart disease that in turn increased potassium levels reaching a level that his kidneys can't cope with.
People reading this may have pre-existing kidney disease; a lot of people with diabetes do. They may already be on drugs that increase potassium levels, (eg ACE inhibitors, very commonly prescribed to people with diabetes , heparin, beta blockers even NSAIDS that people may take for pain others listed in link )http://www.webmd.com/a-to-z-guides/hyperkalemia-causes-symptoms-treatments ( Dr Kendrick's article does mention the risk though he suggests it's small )

All I can say is be careful but preferably get potassium levels checked before supplementing.