Understanding Society User Support

I'm trying to identify the variable of the head of household to be combined with the head data from BHPS. BHPS has this direct indicator, however I searched every data set in the Understanding Society and could find it.

I also searched online and found that the head of household is called the reference person here. It says that people who answered the household survey is the reference person (or head of household). I looked at the household survey data (_hhresp) and there is more than one person who answered the survey (I used the variable _ivh1 to _ivh16).

Could you please help and direct me to the right variable of head of household? Thanks!