The cash outlay you need if you are assigned divided by your total cash available. For example, let's say you are selling two puts, one for stock ABC and another for stock XYZ, and you need to pony up 10000$ each if you are assigned. Total is 20000$.
If that is the case, your account should...
To sell naked options you need a strong balance sheet, relative to your exposure, so as not to be forced to close it at the worst possible moment. Therefore, it should be a very low percentage of your account for all your naked options trades added together.
The exact figure is up to your risk...
Were you trying to go long before the pump or short before the dump?
If I may ask, what kind of indicators were you using to predict the pump, for instance?