A suggestion for the website

[xTcR | Kottonmouth [MP]]

should have a tag of some sort under a site members name that says there in game name for RP servers >.> make it a lil easier to identify whos who lol just sayin ^_^ <3

[Lone Wanderer <??"?]

You can always edit your signature and stuff to display your ingame name. The one problem with this for this kind thing is that aside from HRP, there's HL2RP and OCRP, with OCRP having a name-ish, and HL2RP having multiple characters. Aside from that, admins can see this information and stuff, so yeah.

tl;dr: add it to your signature/custom text via profile editor