It can be a little bit of a pain to figure out exactly what you need to do when it comes time to re-balance a portfolio. There are a couple options.
Pull up your portfolio in your discount brokerage account and look for the total current market value of all of your holdings.
Subtract $50 or so in order to build in a little cash buffer to pay for commissions. Plug this number into the portfolio cloning tool and write down the output.
This is the portfolio you want to get too. Now you just have to buy or sell the appropriate number of shares to get there. So for instance, if you have 121 shares of VTI currently and you want to have 98, then you need to sell 23 shares.