I suggest you consider some features relating to the credit market (which may enhance the spillover effects of FDI), the private investment (there may be crowding out effects of FDI on private investment), the competition between private sector and FDI.
As you know, the credit market (especially in developing contries is very important to boost the capital flow from savers to borrowers) has the main objective in boost capital flows. So you can consider to the credit to GDP, the non - performance loans (which indicate the risk), the competion index (such as HHI, CR5), the ratio of capital to total asset, the percentage of firms that use loans from bank...ect
Important indicators to consider are private sector investment (gross fixed private capital formation (% of GDP), investment in infrastructure with private participation, private foreign direct investment, net (% of GDP)), domestic credit to the private sector (% of GDP), and individuals using the Internet (%).
The profit margin, as a financial measure, is also the most commonly used performance measure. Customer satisfaction is the most commonly used non‐financial measure of performance evaluation.
real GDP, interest rate, inflation rate, tax rate, exchange rate, population growth rate, unemployment rate, trade openness, educational enrollment, broad money supply, and external debt are the most commonly used to measure the private sector.