Critical Strike and Damage Penalty

[Tommi]

I have a question. Critical strike (and deadly strike) modifies total physical damage. Damage penalty from skills, such as Multiple Shot, modify total damage, too. If I score a critical strike with Multiple Shot, do I get

1.5 times normal damage ( (1-0.25)*2 ), or
1.75 times normal damage ( 1-0.25+1 ) ?

That is, do these effects get first summed up or do they multiply total damage separately?

Thanks in advance,

Tommi