On typing Sinhala characters

Dear List-members,

I've been learning how to type Sinhala characters for Pali using a Sinhala
keyboard layout from Microsoft and a unicode font. I have been encountering
some problems finding the right keyboard  combinations for certain letters.
The one I'm trying to solve is how to type in a medial or final o. For
example, although I can type ke (ctrl+alt f, k), I have not yet been able to
type ko which has a symbol before and after k. Does anyone know the
keystroke sequence for inputting the o?

Thanks & best wishes,

Jim