I am quite torn. I really like the RoTRL and now that I've read quite a bit into like it even more. But some other people's posts, such as Story Archers post about the goblin unnecessarily drawing attention and possibly spoiling fun to be a big factor in making me reconsider. However, I may have a solution and was wondering what you guys thought.
For the goblin, I was going to start him out as an outcast from the local Sandpoint tribes, similar to what other have done. But because he is an alchemist with cure light wounds as one of his first potions, I was thinking he may have some tenuous dealings with Sandpoint, even if not fully welcome, selling potions to the temple and maybe some others so that many of the villagers know about this rogue goblin even if they don't fully trust him. He would know something about the initial raid and try to warn the Sheriff, Mayor etc. but not be believed however, afterward he would have some trust with key people like the mayor, sheriff etc. who know about this. This would allow him to at least interact directly with these characters.
Because we have big barbarian, the goblin can be carried around in a sack by the barbarian that will let him travel with the party unseen in populated areas so he's not the center of attention. He can whisper to the barbarian to participate by proxy in conversations. If he wishes to participate more fully he can purchase, go on a side quest or invent some alchemist potion to let him disguise more fully (with the illusion of halfling or polymorph or some such thing) when traveling in a city.
If he has set on making an Alchemist, then my first thought would be to make him the clandestine contact of the proprietor of The Feathered Serpent (the local magical shop) - the owner buys potions from him and sells them for a profit, and it'd be up to you to decide if the relationship was a mutually beneficial one or an exploitative one. Alternately he could be an acquaintance of Madame Mvashti from one of her many long walks through the local environs. Either way, one of the PC's could discover the relationship or the NPC could step forward and 'vouch' for the goblin when it appears there is need for him.
In our campaign, before the PC's ventured down into the catacombs they realized that non elf them had dark vision and elected to 'volunteer' our resident Goblin to join them, instructing him to scout ahead (and watch for/spring any traps he may encounter). At that point the group was kind of treating him like he was expendable, with his character not yet having endeared him to the others although out-of-character everyone was fine and having fun. The point is that if he offers something (like dark vision or magical healing) that the PC's might be in need of, that becomes a very good way to introduce him into an encounter and eventually the AP as a whole.