So in your szenario, you would be tax resident in Portugal (you already moved out of the country of Switzerland to Portugal, when doing the withdrawal)
In this case, the canton where the foundation is will be responsible for levying the tax. In Schwyz, you can find the percentages here :
here
Now for Portugal you would have to check the Portuguese-Swiss DTA as well as Portuguese Tax law if capital payments out of pension funds are taxable in Portugal.