I've wondered for a while about it. Apothecary's are able to extract the geneseed and special organs from a dead space marine, so are they able to create a space marine or do they not have the proper knowledge in order to transplant the geneseed and organs.
Provided an Apothecary has access to the required equipment, gene-seed and a suitable applicant then yes they can make a space marine.
"Outside of combat, Apothecaries are responsible for monitoring the Chapter's Neophytes for mutation or flaws in their gene-seed and organ implants and for carrying out the implantation process in their Chapter's Aspirants." - from the 40k wiki
Note that these things do however vary between apothecaries, though how much is unclear. Some apothecaries are probably more used to working in teams and would thus have difficulty doing the process alone, while someone as skilled as Fabius Bile would have absolutely no problems conducting what to him is a fairly mundane procedure alone.