The combining dot above right is added in Source Sans Pro 3.006, but the usage of this diacritic is not perfect, this mark has some inconsistency with other diacritics or without.
The following letters can produce this problem:
Ó͘ ó͘ (second tone)
Ò͘ ò͘ (third tone)
Ô͘ ô͘ (fifth tone)
Ō͘ ō͘ (seventh tone)
O̍͘ o̍͘ (eighth tone)
BabelPad:

LbreOffice:

See: https://commons.wikimedia.org/wiki/File:Tai-Oan-Hu-Sia-Kau-Hoe-Po.jpg
This is a photo from the 1st issue of Taiwan Church News, which has some examples for this.
The combining dot above right is added in Source Sans Pro 3.006, but the usage of this diacritic is not perfect, this mark has some inconsistency with other diacritics or without.
The following letters can produce this problem:
BabelPad:


LbreOffice:
See: https://commons.wikimedia.org/wiki/File:Tai-Oan-Hu-Sia-Kau-Hoe-Po.jpg
This is a photo from the 1st issue of Taiwan Church News, which has some examples for this.