DoraTheExplora

I wish that there will be a mod store right in the game or in a different program that will keep the mods up to date. It could take less time to install and uninstall mods. So hyped about this new lspdfr though !!

try searching online for solution
 
run it as admin
you can also try these 3 steps
name your gta folder to Grand Theft Auto V
Install the latest version of RageNativeUI.dll it should be atleast 95kb
Install the latest version of AlboCommon.dll it is on LCPDFR in the misc section in mods

screenshots
this is how mine is setup

rph has already been update the same with scripthook go to their site and download it

Try running RPH as administrator. Mine doesn't open if it's not running as admin either.
 
EDIT: Nevermind, didn't see that you've tried it.

... what does your task manager say under Details or processes....look for GTAV or GTAV launcher...if you have multiples in there, end them all, same with rage.exe

It needs to be exactly "Grand Theft Auto V" for RPH to work.

is the GTAV folder named GTAV or Grand Theft Auto V? rph seems to only like the later of the names. are you using Steam, CD, or...other.....

No. Watch on this website: http://www.dev-c.com/gtav/scripthookv/. Where it says; "Supported patches", wait for that to show 1.0.1032.x on it.

RAGEPluginHook has recently been updated and ScripthookV has not. You will NOT be able to play LSPDFR until ScripthookV has been updated.