Reethesh is a south Indian transliteration of what in a typical North Indian translation would be Ritesh. In Sanskrit, the name would have been Rtesha, where the R itself is vocalic (think krrrrrrrng as in a telephone ringing or krrrr as in a branch breaking, just shortened to the length of a short vowel as in English hit) and without any additional vowels, and in some modern Indian languages is transliterated and pronounced ru- instead of ri-. The -a in Sanskrit is the sound at the beginning of the English word about, but disappears in most modern Indian languages; the t- is soft as in French tu, the sh is roughly as in English sugar, and the -e- is long as in English late. Stress is not a feature in most modern Indian languages.
I would roughly translate the name as `master of truth' (I am suddenly reminded of a poem, I forget by whom, `Happy is he born or taught that serveth not another's will, Whose armour is his honest thought, and simple truth his utmost skill ...', oh well, must be getting old to go so off-topic).
For slightly more discussion, see my previous post on this topic at http://www.behindthename.com/bb/arcview.php?id=162403&board=gen