A small selection of Roman UTF8 fonts with support for diacritical marks according to ISO15919 usable under free / open licence.

Fonts - Schriften für Devanagari und Lautschrift (ISO 15919)

Chandas and Uttara

Format: ttf
Variants: regular
Support: Devanagari, Latin (ISO 159199 with extensive coverage of letters with diacritics), Cyrillic (Russian and other Slavic languages)
Stats: 5,092 glyphs and 1,597 kerning pairs. 4347 glyphs: 325 half-forms, 960 half-forms context-variations, 2743 ligature-signs
Designer: Mihail Bayaryn
URL: www.sanskritweb.net/cakram/
License: GNU General Public License
Release Date: 2008 (Version 1.2)

In the roman charset of Chandas and Uttara are identicl. Both supporting vedic accents (Only usual Ṛg Veda, but no Sāmaveda accents).

Download: chandas.ttf (Version 1.2) | uttara.ttf (Version 1.2)

Siddhanta - Bombay, Cakravat, Calcutta, Nepali

Format: ttf
Variants: regular
Support: Devanagari, Latin (ISO 159199 with extensive coverage of letters with diacritics), Cyrillic (Russian and other Slavic languages)
Stats: 1,980 glyphs and no kerning pairs
Designer: Mihail Bayaryn
URL: www.svayambhava.org
License: Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License
Release Date: 2011 (Version 1.000)

In the roman charset all Siddhanta fonts are identical. All supporting vedic accents (Only usual Ṛg Veda, but no Sāmaveda accents).

URW Palladio

Format: ttf
Variants: regular, bold, italic, bold-italic
Support: Roman with diacritic marks
URL: sanskritweb.net

The font company URW++ Design & Development GmbH, Hamburg, and the world-famous typographer Professor Hermann Zapf, Darmstadt, generously donated Prof. Zapf's font URW Palladio to Ulrich Stiehl, Heidelberg, granting him permission to modify and to add diacritical characters not contained in Prof. Zapf's URW Palladio and to offer specialized URW Palladio diacritics fonts to Indologists, Buddhologists etc. free of charge.

Supporting vedic accents (Only usual Ṛg Veda, but no Sāmaveda accents).