how do i write
how do you write "rest in peace" in spanish
Descansa en la paz or in familiar form descansas en la paz but I don't know how it would be written as an epitaph on a grave for instance there might be an idiomatic expression for this, you need to get it from a native speaker.
Que en Paz Descanse. Q.P.D. same as R.I.P. That is what people actually write on graves, but you don't say that to the family, it is better to say:
"Lo siento mucho"
"Acompaño su sentimiento"
a formal way is:
Mis mas sentido pesame.