  In the framework of the relativistic quantum molecular dynamics approach
({\small RQMD}) we investigate antideuteron ($\overline{d}$) observables in
Au+Au collisions at 10.7~AGeV. The impact parameter dependence of the formation
ratios $\overline{d}/\overline{p}^2$ and ${d}/{p}^2$ is calculated. In central
collisions, the antideuteron formation ratio is predicted to be two orders of
magnitude lower than the deuteron formation ratio. The $\overline{d}$ yield in
central Au+Au collisions is one order of magnitude lower than in Si+Al
collisions. In semicentral collisions different configuration space
distributions of $\overline{p}$'s and $\overline{d}$'s lead to a large
``squeeze--out'' effect for antideuterons, which is not predicted for the
$\overline{p}$'s.
