Font missing Characters Latin 1 Supplement. How to type them? I am typing in sanskrit, so, when typing in roman alphabet I need some supplements like  ā ṣ ḥ ś ī.

My font for the Roman alphabet is DV1-TTGanesh. When installing it (I have the copyright version), it says in the specification that it contains the Latin-1 supplement that covers those characters.

The thing is that when I write with that font, everything is ok until I try to use one of those letters that is composed of a dot and vocal, for example ī . Then, the font changes to Helvetica, for example.

At first I thought that the font didn't have those characters, and that was why it was changing the font.

But I figure out, that is not true. The reason is that I opened a text already written by another person, using DV1-TTGanesh, and those letters composed of 2 things, are nicely in the correct font, and are not changing.

So meanwhile, I have to copy the letter I need and paste everytime from one document to another.

So my question is, where are those letters? How can I find out how to write them? I use the keyboard screen but they are not there. There are just showing the elements separately.

Any clues?
To write transliterated sanskrit you normally use the ABC Extended (formerly called US Extended) keyboard layout.  To activate that you go to system preferences/keyboard/input sources and use the plus and add buttons, then you select ABC Extended in the "flag" menu at the top right of the screen.

The shortcuts for making the various diacritic marks you need are given in

http://symbolcodes.tlt.psu.edu/accents/codemacext.html

macron above is option a, then the base letter.  dot below is option x, then the base letter.  acute above is option e, then the base letter.  āḥś

From information you provided in the Apple forums, I think you may be using a Non-Unicode font, in which case the ABC extended keyboard will not produce what you need.  If this is the case, I strongly recommend you switch to Unicode, which has been the standard for this kind text for a long time already.  A non-Unicode font will make your work pretty much unusable for anything other than printing on paper.