library(rfPermute)
set.seed(12)
sahdrfp <- rfPermute(as.factor(chd)~., data=sahd, ntree=100, nrep=100)

#Plot the null distributions and observed values.
par(mfrow=c(3,3))
plotNull(sahdrfp)

#Plot importance distribution 
plot(rp.importance(sahdrfp, scale = FALSE))

#Here are P-values
sahdrfp$pval