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/