I have an rns song in which I’ve loaded a bunch of 96 kHz 32 bit float waves. Seperately, these add up to 29.8 MB, but the song is only 24.4 MB in size, and even contains an additional ITI instrument of 13.4 MB. Are the samples simply comrpessed within the song, or are they rounded or truncated down to a supported bit depth? I hope not… 
I’m not 100% sure about which audio format Renoise uses to compress samples, but I think it’s FLAC. Either way, it is indeed lossless. 