UserX
Magnesium chloride is sold here in little sachets of 20 gr, I pour them in the bottle of Evian, keep it in the fridge, I am not aware of Mg oil sale here. What I sometimes do is to pour a little bit of water inside the sachet and use the oily stuff on my hands that not bad on the crapiness and age spots on skin.
For potassium, the idea is, in my eyes, to increase total daily input of potassium.
Let us say if you consume a lot of vegetables and fruits you have certainly 5 grams or more in your body, fine.
If you add potassium chloride like e.g. Ginagirl said 3-5 grams, it means she is adding 1.5-2.5 grams of potassium-element to her daily consumption of potassium from food which, I am sure, is about more or less recommended 5 grams.
So, that means her daily total input is about 6.5-7 grams of potassium element and she is very close to what the studies of Yamanomi Indians found i.e. 8.3 grams is their daily consumption of potassium, and those guys were aparently very healthy.
However, she is still rather far from what is estimated that all these Paleo guys consumed - about 13 grams.
Hope it helps...