Following is a response from DHS Technical Specialist, Shireen Assaf:
The following code should work for a KR PR merge. I'm using the Rwanda most recent survey as an example.
use RWKR70FL.DTA, clear
rename v001 hv001
rename v002 hv002
rename b16 hvidx
* dropping those that are not in the household so we can merge with PR file
drop if hvidx==0 | hvidx==.
sort hv001 hv002 hvidx
save temp.dta, replace
use RWPR70FL.DTA, clear
sort hv001 hv002 hvidx
merge 1:1 hv001 hv002 hvidx using temp.dta
erase temp.dta