VOICED ADVANCED UVULAR TRILL [ʀ̟]
Tiberian Hebrew resh is not pronounced like any English sound. It does sound, however, like one version of the French "r". To pronounce Tiberian Hebrew resh (in most instances), the tongue should be in the same position as when you pronounce qof, but make a "gurgling" sound low in the back of the throat and vibrate the vocal chords. It is important to distinguish this sound from gimal rafe, which is pronounced in the same place but without the "gurgling" (i.e., with a smoother more consistent flow of air).
This is known as the "light" variant of resh in the Tiberian tradition. Note that in the environment of the consonants דזצתטסלן, Tiberian resh has an emphatic "heavy" variant.
Geminated resh appears to have been vocalized with this primary "light" realization of resh.
PHARYNGEALIZED APICO-ALVEOLAR TRILL [rˁ]
In the environment of the consonants דזצתטסלן, the Tiberian resh is pronounced as an apico-alveolar emphatic trill. Specifically, this variant of resh occurs in three instances:
(i) when it is touching a preceding consonant from among this group (דזצתטסלן)
(ii) when resh is in the same syllable or foot as a preceding consonant from this group (דזצתטסלן)
(iii) when resh is touching or in the same syllable/foot as a following ל or ן
To pronounce this emphatic variant of resh, the tip of the tongue is roughly in the same spot as when you pronounce the "d" in English, but curve the tongue to make a cavity in the mouth for the emphatic sound and pronounce the resh with a trill of the tongue.
SOURCES AND FURTHER READING
Khan, Geoffrey. 2020. The Tiberian Pronunciation Tradition of Biblical Hebrew. Cambridge: Cambridge and Open Book Publishers. §I.1.20.