A magus doesn't gain Spellstrike until 2nd level - that's the one that applies to melee touch spells.
Your example would play out like this:
Str 14
Dex 12
BAB 0
Acid splash prepared.
Assuming no other modifers.
As a full round action, the magus would make a single scimitar attack at +0, dealing normal damage (1d6+2). He would then cast acid splash as part of that same action, making a ranged touch attack at -1 for 1d3 acid damage.