Best soln is to integrate R linear algebra:

> as.matrix(data2) %*% unlist(data)
# [,1]
#[1,] 106
#[2,] 140
#[3,] 140
#[4,] 151

or you can sweep:

> rowSums(sweep(as.matrix(data2), 2, unlist(data), `*`))
#[1] 106 140 140 151

Where data is:

data=data.frame(a=4,b=6,c=8,d=5)
data2=data.frame(a=c(3,5,4,3),b=c(4,6,6,5),c=c(5,8,6,8),d=c(6,4,8,9))