I'm working on a 25 point build alchemist for a campaign my brother is going to be running. Basic concept for the character is a frontier tanner turned adventurer, who eventually gets into the habit of hunting dragons for his profession (taking the dragon crafting feat asap) with the help of homemade poisons fired from a bow/crossbow. At first I thought about going with a Slayer build and just spending the skill points for the alchemy portion of things, but the Vivisectionist works so well I think I'm going with that as my primary class.
Any help planning out this build is much appreciated; character starts at level 1 but I'd like to plan it out at least to level 10. For synergy purposes, his companions consist of a spell caster cleric, a TWF Ranger, and a Sorcerer.
Necessary feats for archery are point blank shot and precise shot, and at least one of deadly aim, rapid shot and manyshot. Preferably more than one. That assumes a bow; light crossbows add rapid reload as required, heavy crossbows need that and crossbow mastery, and neither can get manyshot.
There are extra feats available for doing tricky stuff (ranged feint, combat maneuvers especially w/crossbow or fighting with a bow in melee mainly) but they're not required at all. A vivisectionist may want shadow strike.
Emergency melee may want the feral mutagen discovery and possibly weapon finesse. Probably a bunch of your discoveries are going to poison use. Spontaneous healing and tumor familiar can be useful discoveries too.
The hard thing about a Ranged Vivisectionist is that the things I'd usually use in the Alchemist tool box to take opponents' Dex mod to AC and lock in Sneak Attack Damage mostly involve Bombs, and that is what you are giving up by being a Vivisectionist.
Necessary feats for archery are point blank shot and precise shot
If I want a Ranged Character, I usualy start off with a level in Fighter just to make sure I take Precise Shot at level 1.
I have a Ranged build that starts like this
Half Elf, Arcane Training, Ancestral Arms: Orc Hornbow
1Fighter1: Point Blank Shot, Precise Shot
2F1Ninja 1: Sneak Attack 1d6
3F1N2: Ki Pool, Ninja Vanishing Trick, Extra Trick: Rogue Talent: False Attacker
Ninja Vanishing Trick only last for 1 round, but even 1 round of Invisibility means you can just about always use Stealth then and find yourself a good hiding place to snipe from.
Normally, you break cover when you attack from a place of Stealth: -20 on the check! But with False Attacker, you just need to win a simple Bluff/Sense Motive opposed roll. If you win, you get to stay in Stealth; if you lose, you then have to make that Stealth Check.
Another Ranged Sneak Attacker build I have:
Fighter1: Precise Shot
2F1Bard1: Flame Dancer, Bard Stuff
4F1B3: Song of Fiery Gaze
5F1B3Brawler1: Snakebite Striker, Sneak Attack 1d6, Accomplished Sneak Attacker +1d6
Song of Fiery Gaze gives you and all your allies the ability to see through fire and smoke. So this character casts Pyrotechnics or acquires a Horn of Fog or an Eversmoking Bottle, which makes everybody else Blind, and that mean you get your Sneak Attack Damage, and you just gave your whole party Total Cover.
Alchemists do get Invisibility and Greater Invisibility, but invisibility is only good for 1 attack, and Greater Invisibility comes late. Likewise the Echolocation spell works with the Eversmoking Bottle kind of like the Song of Fiery Gaze does, but it is also comes late in the game: a level 4 Extract.
If you take 3 levels in Fighter with the Archer Archetype, you can Feint with your bow.
The Dirty Tricks Combat Maneuver can Blind an opponent. But Combat Maneuvers are usually a melee thing.
Canny Tumble denies your opponents their Dex Mods to AC if you successfully Acrobatics your way through a Threatened Square. I guess you could then keep on going, turn around and shoot your target and get SA Damage that way.
Honestly, though, for a Range Sneak Attacker, I'd use one of the builds above, maybe taking levels in Vivisectionist later. If I wanted a Ranged Alchemist character, I'd go with Grenadier or Gunchemist and go for the exploding arrows or exploding bullets.