I just found out about it by watching LOL streams online
This link was posted in one of the comments. This will enable you to use smart cast with range indicators by holding down the skill buttons Q/W/E/R
TO ENABLE IT IN LOLph FOLLOW THE INSTRUCTIONS:
STEP1: Go to your Garena Messenger folder then proceed to Apps/lolph/Game/DATA/CFG
STEP2: In CFG folder look for the file game.cfg right click then open with notepad
STEP3: In your keyboard press CTRL+F to open Find function then type in SmartCastOnKeyRelease
STEP4:On the SmartCastOnKeyRelease line change the 0 to a 1
HOW TO USE:
1. You have to enable auto smart cast in the in game option or holding SHIFT+ skill buttons Q/W/E/R
2. You then hold Q/W/E/R buttons this will show you the skill's range then release to fire the skill wherever your mouse arrow was pointed at.
3. This works even by simply pressing the skill buttons it will show you its range briefly while simultaneously firing the skill
NOTE: IN ORDER TO CANCEL THE SMART CAST JUST RIGHT CLICK WHILE STILL HOLDING THE BUTTON
NOTE: I tried this and it worked.
This guide is for people like me who are new to LOLph and didn't know about this function.
PS: I like to use smart cast on skills but sometimes had trouble on estimating the range on champion skills, I am pretty sure I am not the only one so I hope this helps.