Randomly selecting eligible respondents from a roster

I have looked through the online documentation and can’t seem to find any documentation describing how to randomly select an eligible respondent form a roster. I can create the roster easily, but not sure about this step. Thanks for your help!

A discussion of randomization is here: http://siteresources.worldbank.org/INTCOMPTOOLS/Resources/8213623-1380598436379/9346245-1429811612082/randomization.pdf

If you want to only pick one respondent, it’s often simpler to just display the name of the selected person in the instruction to the interviewer to continue the interview with that person.