I know of at least two solutions. The first you could attempt is a
straight-forward hack by using
\textsc{\.{\.i}}
to produce a dotted i (lower case I) in small caps. The following
minimal example produces the correct output:
\documentclass{article}
\begin{document}
\textsc{This makes your suggestion \textsc{Poss\.{\.i}ble}.}
\end{document}
Let me (us) know if this is insufficient.
Werner