r - Specifying the "idp" and the "nmax" in the krige.cv function

I'm performing IDW interpolation using the idw R function from the gstat package. For the purpose of determining what combination of "idp" and "nmax" produces the lowest RMSE in leave-one-out-cross validation, how can I specify the "idp" and the "nmax" that are going to be use in the krige.cv function?