The Prophet ﷺ said: “The most beloved of your names to Allah are ʿAbd Allah and ʿAbd al-Rahman” (Muslim 2132), and scholars add to them all names formed on a name of Allah. The name al-Rahim occurs 114 times in the Quran; its page in the 99 Names section gives its meaning and verses.
ʿAbd al-Rahim joins ʿabd with al-Rahim, from the root r-h-m of mercy: the One whose mercy reaches the believers in particular, while al-Rahman expresses the mercy that embraces all creation. The two names open every surah in the basmala. It is written Abderrahim in the Maghreb and Abdurrahim in Turkey.