just write the consonants in the order they appear without "+", voyels or irregular ༹. (i.e. ཙ, ཚ, ཛ are ts, tsh and dz and for example ཀ༹ is k only)

for instance:

ཀུནས། -> kns

སྒྲུབྱིས། -> sgrbys

ཀླེུནད། -> klnd

དཀྱིུང། -> dkyng

བཀ༹ལ། -> bkl

རྣཾསེ། -> rnMs or rnms