Firstly finding force in vector form

$F = F . rPQ = 1200[(-7i - 4j+8k)/[(\sqrt{7^2+4^2+8^2})] = 739.58 i - 422.62 j - 845.23 k KN $

Now, Finding moment of the force about point $A(3,2,0) $

$MFS = rSP x F .........where\space \space rAP = i + 3 j - 2 k m $

$$MFA= \begin {matrix} i&j&k\\ 1&3&-2 \\ 739.58&-422.62&-845.23 \end{matrix}$$

$MFA = - 3380.93 i - 633.93 j - 2641.36 k KNm $

Moment of force about point is $- 3380.93 i - 633.93 j - 2641.36 k KNm $