HR for startups is different. It's growth-focused and has some unique challenges. There is a lot of recruitment (of course), but also onboarding, and other activities. Some of the challenges may include helping founders get out of their own way.
Maysa Hawwash is the CEO of ScaleX which is a fractional HR company devoted to helping organizations grow. Although sometimes they shrink too because growth is not linear.
Scale X: http://www.scalex.ca/