Do you know for a fact that you have B12 malabsorption?If you eat animal products - meat, fish (and/or dairy, eggs) you are very unlikely to be low on B12 unless you have a clinical reason for not absorbing it. The clinical reasons for not absorbing it are an autoimmune disease called pernicious anaemia (which is not the same thing as iron anaemia), as well as digestive inflammatory conditions such as Crohn's and colitis. Coeliac disease and alcoholism can also cause B12 malabsorption.

The only way people who have clinical B12 malabsorption can get enough levels is through injections. So I'm assuming you haven't been diagnosed with malabsorption, otherwise your doctor would be giving you injections on a regular basis.

Regarding the supplement you mentioned, as I say, unless you have a clinical malabsorption problem, your levels of B12 are likely to be fine if you eat meat or fish (or dairy/eggs) daily. 10mcg is larger than 100% of your RDA. You don't need to take that much, but there's no harm as the body will just pee out the excess that isn't needed. As for whether that level will cause acne - probably not. I have clinical B12 malabsorption and get 1000mcg injections every 2 months and it doesn't make me break out. B12 can cause a break out for some people, but I've personally never had one from it, and I speak as a person who does have spots generally. The B12 has never made my skin worse.