Firstly finding force in vector form

$F = F . rPQ \\ = 10[(8i -6j -k)/[(\sqrt{8^2+6^2+1^2})] \\ = 7.96 i - 5.97 j - 0.995 k KN$

Finding moment of the force about point $S (1, -10, 3) $

$MFS = rSP \times F ...where\space \space rSP = i + 13 j + 2 km $

$$MFS = \begin {matrix}i &j &k\\ 1& 13 & 2\\7.96 & -5.97& -0.995 \end{matrix}$$

$MFS = 0.995 i - 16.92 j - 109.45 k KNm $

Moment of force about point is $0.995 i - 16.92 j - 109.45 k KNm $